NateDawg and Zoolander at Google Blogoscoped point out that asking either of the two search engines about Google has an interesting effect. These search engines utilize some valuable space (that would normally serve advertisements or results) to pitch themselves to the user. I guess there's nothing wrong with that, it is their site and they can do what they want -- and it's less evil than the toolbar feature that actively blocks attempts to change the default search engine in Internet Explorer.
[Images from Google Blogoscoped]
Anyway, this is actually smarter than you would think. At first I wondered why anyone would search for google.com at all? After thinking for a while, I recall teaching "Cyber Camp" to children, and tutoring elderly people on computers when I was a bit younger -- you would be surprised how many of these people use search boxes as their address bar.
For a new computer user who doesn't have much experience, it isn't very clear what has to be done -- they know "google.com" and they know to type it in somewhere. This could be Yahoo and MSN's attempt at intercepting these impressionable people and converting them before they begin searching. I wonder why Google doesn't do the same thing?