Yahoo mail web interface is available from the browser. If you are a paid yahoo subscriber, they offer POP access, so you could configure your mail reader using POP. As far as I know, IMAP is only offerred (free, too!) for iPhone users. I am hoping Yahoo opens this up to everyone soon as a one-up thing to Google Mail.

Yahoo IM can be done using Pidgin. It can also be done using the built in IM tool via jabber, but I haven't figured out yet how to do this. Pidgin works well for me so I don't have a compelling reason to figure the jabber stuff out. Now if one could video conference over jabber/Yahoo IM, then I'd be all over that!

-steve