I don't like cables so I picked up this Apple TV a couple of weeks back. I have configured an Apple TV and placed near the projector. It connects to projectors via HDMI. iPhone 4s and iPad 2+ users can mirror their screens wirelessly via airplay (connect to
hackerspace.sg ssid). Once the Apple TV is turned on, the airplay icon will appear on the iOS dock, next to the volume icons. See image
http://www.flickr.com/photos/preetamrai/7159162289/in/photostream.
This airplay feature will come to Mac OS in Mountain Lion. And we can watch movies on it too.