The rationale of the agenda for this weekend's G20 leaders' summit is obvious. After all, the mounting financial crisis is a global phenomenon requiring common corrective measures.

Less obvious, however, are the individual roles of the G20 participants that will sit for dinner tonight and deliberate on Saturday. The leaders selected for the summit's list of invitees directly replicate the innovative and successful G20 constellation of finance ministers and central bank governors that first met in 1999 to address the fall-out of the Asian financial crisis. Yet, in the rush to accept the forum's prevailing membership, there does not seem to have been a reconsideration of which systemically important countries need to be around the table.

In the 10 years since the founding of the G20 Finance, the global economic order has changed, reflecting changes in performance of the forum's participants. The most significant change is in the role of the host of this week's summit. During the 1997-98 crisis, the United States was comfortably in charge, telling the Asian countries what they should do in terms of a rescue package. While in 2008, the world's leading economy is on the receiving end of a storm of criticism about its financial and broader economic practices.

But this is not the only change. In Europe the crisis has brought together the "odd couple" of the mercurial Nicolas Sarkozy of France and the U.K.'s dour Gordon Brown as advocates of immediate and long-term corrections, including a new Bretton Woods system.

By way of contrast, Germany (the convener of the first meeting of the G20 Finance) has lost its reputation as a consensus-builder. Instead of pushing a confident brand of multilateralism, the government of Angela Merkel has seen a reacting haphazardly from event to event. Italy is perceived by some to be compromised by the diplomatic gaffes of Silvio Berlusconi, particularly as it ramps up to host the 2009 G8 Summit. The disdain with which the Italian prime minister is held by his European counterparts is more sharply drawn when it is compared to the steely determination of the Spanish government in pushing for its right to sit at the G20 leaders' table (a claim facilitated by the willingness of France to give its second seat at the table, in the form of the EU presidency, to Spain).

The scale of change in the balance of world economic power is even more dramatic when attention is turned to the core set of emerging powers. In 1999, China, India and Brazil were invited to take part mainly on legitimacy grounds. In 2008, their participation no longer has any traces of symbolism. These countries -- with their huge currency reserves and increasing economic size and growth -- not only deserve but are needed to be in attendance. Similarly, while Saudi Arabia may not be the sentimental choice of many of the other participants, its participation as a major economy has been reinforced amid the credit crunch.

If the original G20 Finance group brought together states perceived as problem-solvers, it also includes countries that were seen as part of the problem. Albeit not free of other difficulties, some of these countries -- most notably Mexico and Russia -- have moved into a very different economic position over the last 10 years. Others however, such as Argentina and Turkey, appear to be in danger of sinking back into financial peril.

The trajectory of regionalism has also undergone transition. This is most obvious in Asia, the home of the financial crisis of the late-1990s. That period was notable for the intense rivalry between China and Japan, a friction that blocked the so-called Chiang Mai initiative for an Asian regional monetary fund. And yet, one of the striking features of the 2008 crisis has been the willingness of China, Japan and South Korea to support broadly similar ideas, including those related to improved transparency, better self-regulation, expansive fiscal policies, and aversion to trade protectionism.

Two other categories of countries continue to be given entrance tickets to G20 forums. The first are the classic middle countries of Canada and Australia. Nonetheless, what jumps out is the shift in the logic of this participation. In the 1990s these countries were assumed to be diplomatic innovators, a brand highlighted by the role of Paul Martin (Canadian finance minister of the time) in bringing the G20 Finance to life. Now what these countries offer are models of successful domestic financial governance -- in Canada's case, the best in the G7. Such a role, while more low-key, is no less demanding.

Canada must actively ensure its relevance to whatever G-club emerges from the financial crisis. Canada must continue to strengthen its capacity and willingness to "punch above its weight" with sound and successful domestic economic policies, and promote innovative ideas for a robust international system capable of addressing future crises.

The second added category are the countries that have been given the right of attendance by geographic representation. Indonesia won this right over competitors in Southeast Asia such as Malaysia in 1999 and has hung on notwithstanding a well of domestic political and economic concerns. In similar fashion South Africa has continued to be invited as the sole country from the African continent, despite the claims of Nigeria and Egypt.

This status quo element points to the existence of some degree of continuity amid the ample forces of change within the G20 constellation. And this is not the only sign of a "back to the future" dimension located in the upcoming meeting of G20 leaders. One component that amplifies this trend is the revival of interest in the International Monetary Fund -- a key participant in the G20 summits -- as the lender of last resort and home to improved monitoring and surveillance, one of the key elements of reform.

Another is the return of the cohort of U.S. policymakers who aided and abetted the U.S. primacy in the G20 Finance in the first place. The call to this form of summitry may be a last-ditch effort of President George W. Bush, but this type of forum is deeply embedded in the policy toolkit of key advisers of the president-elect, such as Paul Volker, Lawrence Summers and Robert Rubin who were present at the creation of the original G20.

If perceived by the rest of the world as a flop, Mr. Bush's grab at this initiative could make these figures more reluctant to do an event of this nature during the administration of Barack Obama. If it passes expectations, however, we will likely see more of this G20 experiment, and a fuller debate about its composition.

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