It turns out that last night's story about that
Devil on G-string manga adaptation based on Akabei Soft2's wicked
eroge was just the titillating tip of the iceberg. Aside from that, 6 other manga have also been advertised to begin serialization in Kadokawa Shoten's Comp Ace magazine, starting with its July issue (out in May).

So then, here's the (full?) list of new manga titles, via
ANN.
- Shin Strike Witches (New Strike Witches, tentative title)
- Canaan
- Shin Koihime Musou (True Koihime Musou)
- The Devil on G-string (G-senjou no Maou)
- Summer Wars Gaiden (Summer Wars Side Story, tentative title)
- Angel Magister
- Valkyrie Complex
Most of the above titles are originally based on games:
Canaan (from the 428: Fuusa Sareta Shibuya Wii game),
Shin Koihime Musou,
The Devil on G-string,
Valkyrie Complex and apparently
Angel Magister - an upcoming eroge developed by Mana (
School Heart's,
Mare Mare Mare). The first 3 of these also have anime adaptations planned for later in 2009, by the way.
Strike Witches needs no introduction, I figure. And as for
Summer Wars, I should note that a Summer Wars manga was also
announced just a few days ago to begin serialization in that new Young Ace magazine, from July 2009. No idea if it's the same manga or not, though.