While we're still in the process of adding and trimming the player's building material selection for the next version, we think we've hit on a nice group of 2d blocks for players and mappers to play with. We're still working on the 3d block set, so any good pics of those are yet to come.
What's most striking about the new SF2 blocks are the new damage levels - blocks will appear to splinter and crack as they recieve damage. Dark creases appear and if damaged enough, blocks break apart into a shower of pieces.
Through feedback one of the most often commented on features of SF1.9.X that we received was that players either didn't know that blocks could be damaged, or had difficulty recognizing if blocks were damaged when they were in a shadowed area. Hopefully specific damage indication provided by this new system will both expand player's building capabilities while also making the block health system more intuitive and apparent. Not to mention making block destruction all the more satisfying!