johnnie - 8:00 am on Mar 2, 2009 (gmt 0)
The action system can be left untouched. All G will have to do is store a publisher's income in USD. Google charges advertisers in euros, so they're basically either creaming off the top (if the USD is tanking in the meantime) or taking the hit (when the USD is gaining relative to the euro, as is now). Given adwords policy, it would be fair to place this burden on the publisher.
I imagine it would be complicated to have an auction system with different currencies, and that it is just simpler to convert everything to US dollars before it gets in the system.