"Raiden" means "thunder and lighting" in Japanese.
Metal Gear Solid creator Hideo Kojima is involved in the project, but merely as the game's executive producer and not as the title's writer or designer.
Long waits for Metal Gear Solid games are not uncommon. Metal Gear Solid 4 was first shown at the 2005 Tokyo Game Show. It wasn't released until June 2008.
[Source: Kotaku]