Planet13 - 11:42 pm on May 31, 2011 (gmt 0)
Apparently there is a (relatively) new video on YouTube with Matt Cutts where he addresses this issue.
Axandra's Weekly Search engine Facts newsletter has this summary of what Matt Cutts says regarding server location:
7. The IP address of your website can influence its rankings
If you want to get high rankings on Google.fr, it helps if your website has a French IP address. Websites that do not have a French IP address can also get high rankings but a French IP address helps.
Just something to think about.