The initial pictures sent so far are from their "HazCams" - 1Meg sensors. As bandwidth is very limited, these were down-sized to 64*64 pics for the first images.
http://www.360pano.eu/show/?id=731
This is the 360-degree panoramic view from NASA's Curiosity rover on Mars as seen by its mast navigation cameras. The main imaging sensors are by "Truesense".
http://www.truesenseimaging.com/blog/entry/2012/07/30/the-other-half
And Curiosity also tweets!
https://twitter.com/MarsCuriosity