3DS (and PC) version of Sonic Generations, and a new Shinobi game. It turns out that the latest issue of Nintendo Power announces them both before Sega has a chance to fire up the press release machine.
The cover of the June 2011 issue, as found on NeoGAF, specifically notes that Sonic Generations "speeds onto the 3DS" just in time for the sometimes pudgy hedgehog's 20th anniversary. Shinobi, however, is only listed as a "classic revival."
Additionally, a teaser of the forthcoming Shinobi game appears to have leaked on YouTube, posted yesterday by user "greatshow482" -- the user's only upload. Beyond affirming Griptonite Games as the developer, the teaser confirms a Shinobi game "re-imagined for the Nintendo 3DS."