Yahoo! Messenger (and Adium with Yahoo! Messenger accounts) have the functionality to send IM-to-SMS (phone texts) messages.
In Yahoo! Messenger, there is a menubar entry, under File, called "New SMS". When that is clicked one, a little dial pad pops up, and you can dial in a phone number to, basically, send texts to through your IM address.
Now, Adium has the -ability- to send and receive these messages, but there is no menubar entry, no easy way to start such a conversation.
My suggestion is to add something to mimic this pair, the menubar entry and little dial pad. Also! There is no reason I know of that this can't be integrated into contacts. So, to be able to add a phone number to a contact from a yahoo address, and possibly to integrate Address Book app into that, and pick up those phone numbers?
Is this feasible?