Meh, the whole thing smacks of the Apple executives spending all their time using Mail, and thereby want to place all of these unrelated features in there. I mean, they obviously don't use iCal.
Up next, Address Book is now a folder in Mail. Followed by a new mail folder filled with forms for ordering lunch. Followed by Mail Widgets. Next up, stock quotes embedded in every incoming email, kinda like a real time ticker if the emails are coming fast enough.