I have been looking at VoIP technology and the associated tools (Gizmo and Skype) for the last few months to see how it can be used in (and outside) the classroom to enable communication … both tools are very cool. Although I believe Skype is more of a peer to peer model, while Gizmo is a real VoIP application. I even switched to Vonage for my home phone — and it is great! I save a bunch of money every month and there isn’t any difference in service. Might be worth a look. At any rate, some people from my new group gave a talk last week about SecondLife — the virtual world software. It was cool that they didn’t all physically show up for the talk, they used the SL space and Gizmo to give the presentation. They even went so far to build a virtual conference room that they all met in and projected that in front of the real room. I think it made an impact — as in, people started to see some interesting application of the whole thing … I wonder if you’d count that as a mash up?