I've seen some questions like this one about video chat on non-Windows platforms. I'm specifically wondering about this in a corporate environment, using an internal server rather than one on the public Internet.
We already host a Jabber / XMPP instant-message service, though I'm not sure what the actual server software is because I'm not responsible for it. From here it looks like ejabberd is a good choice for the server if I have to stand up my own, but other suggestions are also welcome. There's a lot of standards out there and I don't know which one is the best fit.
As for clients, I'm not sure what would support voice/video on both Linux and Windows (at least). We've been using Pidgin but a) I don't have video support compiled in on the Linux side right now, and b) AFAICT the Windows version doesn't support v/v yet. I'm not picky, I just need something that's going to work cross-platform -- I've had problems at home e.g. getting iChat to talk to Google Talk, etc. I hope I'm asking the right questions... I'm kind of new to a lot of the terminology here.