comScore just put out the release this morning:
Share of Local Searches by Site
July 2006
Total U.S. Home, Work and University Locations
Source: comScore qSearch
Total Local Searches
Total Internet Population 100%
Google Sites 29.8%
Yahoo! Sites 29.2%
Microsoft Sites 12.3%
Time Warner Network 7.1%
Verizon Communications 6.6%
YellowPages.com 3.9%
Ask Network 2.7%
Local.com 1.9%
InfoSpace Network 1.9%
DexOnline.com 1.4%
All Other 3.2%
I have a slightly longer post on Search Engine Watch.