The sandy bridge architecture incorporates 2 x sata 6gb/s interfaces.
Yes, anything with a sandybridge chip should have at sata 3.0
It is, of course, possible to build a computer using only the sata 2 functionality but... nobody would. In fact there is some speculation that the intel 510 ssd was designed for fast sequential read and write in order to showcase the chips 'new' sata 3 ports which would be required in order to see the amazing speed of these ssds.
Hope that helps answer your question.