So, on Android Market, I see the app was updated May 5th, 2011. However, I cannot download the app to my Atrix. Any idea what is happening? My device shows up in the list of devices to install to, but it is greyed out.

Any idea what is going on here?

Vendetta is currently only available on tegra2 tablet devices (motorola xoom, asus transformer, etc. Since the atrix is a phone install is disabled (not even sure it should be listed). The atrix hardware is more then capable of running VO, but the interface is not currently usable at the small screensize of a phone. Eventually Vendetta will likely be made available for phone devices, but not at present.