A new Bishoujo magazine titled Comic Sigma+ will be released on 7/24. Comic Sigma+ will be the sisiter magazine of Comic Sigma, another new magazine from Akane Shinsha that will be launched in September.

The first issue of Tokuma Shoten's Comic Ryu will be released on 9/19.

A new Chinese manga anthology called Shounen Longman Sunday (Longman: Dragon Comic) will start in July. The new monthly magazine (comes out on the 1st) will serialize popular Japanese Shounen Sunday series such as Detective Conan and Inuyasha.

French publisher Humanoides has announced a new global manga anthology magazine titled Shogun, which will feature works from European artists.

Two all new magazines specialized in cat manga:

Neko no Akubi: Bunkasha, first issue to be releaesd on June 16 .
Nekodama: Aoba Shuppan, first issue to be released on June 28.

The first issue of a new bishoujo battle magazine from Kill Time Communication will be released on 7/25. The magazine, Comic Valkyrie, is aimed at readers of all ages (while there might be questionable contents from time to time), and will be released every other month on the 25th, for 550 yen.

From Ikaros Shobo comes a new bishoujo magazine called MC☆Axis. The first issue will be released on 6/20.

The first issue of a new monthly shounen magazine from Leed titled Shounen Fang will be released on 7/19 (September Issue).

The first issue of a new magazine from Mediax titled Neko ni Matatabi was released on 5/27.

The first issue of a new adult magazine from Oaks titled Hana Ryou Gakuen Shotou Club (Imperial Flowers Academy Elementary Club) will be released on 6/5. (As if the titles aren't obvious enough, the links are NSFW)