I wonder if it has to do with the fact that Google is really, really slow about updating their index, it seems.
For instance - my old domain, patpaints.net, used to host forums for a political group (because I'm such a nice guy). All the forum pages (and the old, old site pages - we're talking before I used CSS) are still in the Google index, even though the domain leads to a GoDaddy domain parking page (even when it was forwarded to .com, they still didn't update - they just duplicated!). The forum pages have been gone for 4 months or more...
Google: "Results 1 - 6 of about 510 from patpaints.net" (search was 'site:patpaints.net')
MSN: "We couldn't find any results containing site:patpaints.net"
How obnoxious is that?
MSN: 1, Google: 0.