This phone is manufactured by HTC and sold as the T-Mobile G2 in the US and the HTC Desire Z internationally. You may also encounter references to this phone by it's pre-release name, HTC Vision.
HTC Desire Z (source: GSMArena)
Basic features include:
- 800 MHz Scorpion CPU
- Adreno 205 GPU
- 515 MB RAM
- 1.5 GB Flash
- support for microSDHC up to 32 GB
- 3.7" 800 × 480 WVGA Super LCD capacitive touchscreen@ 252 ppi
- 5 MPx rear camera
Full specifications can be found e.g. at GSMArena.