dan404 - 4:50 pm on Oct 30, 2009 (gmt 0)

Major Improvement? Not for me maybe.

About six months ago removed 301 redirects non-www to www from all of my websites after being dropped almost completely out of Yahoo! index. Now both SE's index new pages almost instantly.
BTW Y! most definately prefers non-www.

Not only did Live/Bing referrals skyrocket, Yahoo! did as well.
Go figure. Easiest SEO trick for those two out there(in my case).

Also did some experimenting with 302 redirects with very good results.