Airplay Mirroring: List of working Mac's

Maybe we can collect a list of Mac's with working Airplay Mirroring for a better overview.

As far as I heard, the following conditions must be matched to see if it works:

1) Your Apple TV has iOS 5.1b2 Firmware (only possible with iOS Dev Membership)
2) You are connected via the Airport to your Wi-Fi.

I tried with both my Macs. Unfortunately, none of them is working.

Code:

[B]Not working:[/B]
iMac 27" Mid 2010, Core i3 3.2 Ghz
MacBook Unibody 13" Late 2008, C2D 2Ghz