No need to sign into multiple services to check all your messages on the web.
Instead, you can see any POP-enabled e-mail account (including Yahoo! Mail (Plus), AOL Mail, and Gmail) right from your Hotmail account. You can put all of your messages together in your inbox or each e-mail account in its own folder, your choice.
Read more here:
http://mailcall.spaces.live.com/blog/cns!CC9301187A51FE33!51039.entry