I guess Microsoft launching a search engine in beta version was the headline of this week. If you missed it Scoble has a roundup about what has been commented on it (don't miss this funny aspect).
Leaving from this context BBC is having a very interesting overview of the main players in the search engine arena: Google, MSN, A9, Yahoo and AskJeeves.

Google is Google's biggest enemy, because of their frequent and highly publicized cases of self-censorship (in the US, in France, etc. -- you can use Google to look them up :-) )