Trigger Heart Exelica (a Naomi arcade shmup) is shipping TODAY. There is a good possibility that this will the the second-to-last OFFICIAL release on GD-rom as Sega has plans to discontinue the GD-rom format.
Last Hope (an unoffical game pressed on CD that was ported from a homebrew Neo-Geo game) was released a few weeks ago.
The only other game on the Dreamcast release schedule seems to be another shmup (the only genre keeping the DC alive) called Karous (or "Crow") to be released 3/8/07.
Here's a description of Trigger Heart...
Trigger Heart Exelica is coming from the small Japanese developer Warashi (possibly known to some from the shooter 'Shienryu' and numerous Mahjong games) and is a Naomi Arcade port, originally released in Japanese Arcade not long ago -- in early 2006. It's a vertical shooter with intense single-player shooting through realtime 3D worlds and AI-adjusted boss challenges.
What's unique about Trigger Heart and distinguishes itself from other shmups is the three button system. Next to the usual shooting and bomb button, there's an "anchor shot", which allows you to capture enemies. Once captures, you can use your foes as shield or throw them back at other enemies as sort of special bomb.