Sony's SLT-A55 is not a NEX camera, and while it uses either a Konica Minolta AF or Sony A mount, it does not feel entirely like a Sony Alpha either. This is because the SLT-A55 (and its little brother the SLT-A33) have kept the mirror but forgone the reflex (this is similar to what the Olympus Camedia E-10 used to do, way back in 2000).
The A55 is an APS-C camera, smaller than a traditional SLR but not so small as most mirrorless cameras. It has an electronic viewfinder which helps with 100% frame coverage and 1.1x magnification, but is not a replacement for optical viewfinders in high-speed situations. On the subject of high-speed, the non-reflex mirror means that the autofocus sensor is able to continue focusing even while bursting, giving an outstanding 10fps—limited in its effectiveness as the shooter does not see the updates during the burst. Still, for $750, there is a lot of positives for this camera (including, in the US A55V version, a GPS receiver).