Need to update you guys on two things here:
1. Sonic 3 HD is cancelled because of lack of faith and interest in the project.
2. Sonic 2 HD got cancelled a while ago because of the team's former programmer attempting to sabotage the project and consequently getting booted from the team. BUT, since then the project's come back to life and, even though it's still unfinished, it's now looking more promising than ever!
All the info you wanna know about Sonic 2 HD (including an Alpha Demo) can be found here:
http://info.sonicretro.org/Sonic_the_Hedgehog_2_HD