Use iChat for MSN/Yahoo Messenger
With the release of OS X Tiger comes iChat AV 3. While the video conferencing may not live up to the hype, as you need Dual 1GHz G4’s, or a G5 to initiate a 4-person video chat, the addition of support for Jabber - “an open, secure, ad-free alternative to consumer IM services like AIM, ICQ, MSN, and Yahoo” brings some interesting chat options into the mix. Most notably, you can now use iChat AV 3 as an MSN and/or Yahoo messenger client. While all-in-one applications such as Adium exist, it’s nice to be able to use iChat’s nice interface to handle all of your IM needs.
To add your MSN/Yahoo contacts to iChat check out this How To over at Allforces.com.

June 30th, 2005 at 8:57 am
Webcam via Jabber iChat:
All my friend use MSN messenger on Windows,
and I really want to be able to use webcam with them.
But using Jabber you can’t use webcam on MSN.
Does anyone know how?
(PS. Don’t say Mercury because I can’t find anyone who is able to get webcam to work on that!)
August 6th, 2005 at 8:05 pm
This has been discussed in various places around the web. My suggestion would be to get your friends using Jabber via Trillian Pro. It apparently supports the methods that iChat uses to do video/audio chat.
January 27th, 2006 at 8:12 am
Use aMSN. Works perfect on OSX and supports wabcam:
http://amsn.sourceforge.net/
Harold
September 19th, 2006 at 7:16 pm
aMSN works, but everytime I open it, my CPU usage jumps to a steady 20%. Without it, even running Entrouge, iChat, iTunes, and FireFox, my CPU doesn’t jump above 5-10% and usually stays steady at 2%. aMSN is useful for the video chat, but when I’m not using that, I turn it off.
January 4th, 2008 at 11:35 am
i am an adium user, and recently i discovered a plugin (from the xtras website) called meBeam. basically you right click on your buddy and select “initiate MeBeam videochat” and it opens a browser window where you can video chat with your buddies! there is a tennsy tweaking issue with the settings, but it works perfectly.