Cat is correct about going to Multiply. We talked about the advantages and disadvantage of several sites and it came down to Yahoo and Multiply. The primary reason that Multiply got the nod was because, like MSN Groups, it allows photos to be posted in replies (this is a real bonus, especially if you're trying to show something to illustrate a point) and Yahoo does not.
Also, Multiply is closer to MSN Groups than Yahoo and we figured that it would be easier for folks to get used to.
That was our reasoning and we think it was the best way for us to go since MSN Groups is going away for certain.
The main thing for everything now to do is to get signed up and become part of Multiply so the transistion will be as painless as possible.