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.