I'm a developer (getting ready to release PocketDay for the Blackberry), and I've always been struggling with the fact that I can have only a single return address.
Well, I've come up with a novel, yet workable, solution:
via the developers api, I can change the reply-to address to anything I want. So if I make my bb web client have my
address, but change the reply to, then when the user selects reply, it will go to any address you pick. If they look at the From address directly it will have my bb address, but this solution works for me.
Anyone else interested? I could make it a part of PocketDay. You could set up to 10 different reply-to addresses and I will allow you to compose or reply to emails using any of the 10 addresses for the reply.