You have an outstanding DSLR in your hands.
If you are wanting to go UP from a DSLR/SLT you are looking at going to Medium Format or Pase One, Mimaya, Hasselblad...
What do you need to upgrade?
You choose a camera by what you need-and it's NOT megapixels in any way shape or form.
Are you printing billboard sized prints to be viewed under a microscope? THEN Megapixels will matter.
Are you printing? How big?
WHAT are you shooting? Weddings? Portraits? Landscape? Wildlife? Journalism? Macro? The list goes on and on and on...
Do you need low light capability? Shoot in the near to dark?
Do you need lightning fast frames per second? Sports or similar?
The Sony A77 is pretty damn amazing and that comes from a dedicated canon shooter. Check out Gary Fong's blog and what he has to say about his switch to Sony. He's almost enough to convince me to switch!