Bridging Accounts Across Softwares

[Digital Jedi]

I asked this a loooooong time ago, and at the time, well, let's just say I made the staff giggle with the question. But I'm going to be more specific this time, and maybe there's been a change in things I'm not aware of.

First, am I correct in that you can get a 4.x installation and a 3.x installation to share account information on the same domain? I've been assuming so, based on what you used to be able to do with cross domain modifications, but maybe I understand those wrong.

Second, say I want to design styles for vBulletin and the SMF boards. I would have my styles setup like any styles site would, and I would simply use the forums to post updates and to provide support. Is there any way to get the two different softwares to share the same basic account info? Basically, I'd like to see posts from SMF also go to the vBulletin, and vice versa. But just bare bones stuff. Posts, threads (and maybe attachments) would pretty much be all I need. Things like post count or even avatars is secondary stuff, and not really all that important. I would just rather not have to look at two boards to have to provide support and post updates.