And that doesn't include Insect Armageddon!
It turns out that Earth Defense Force: Insect Armageddon is just one of four titles that D3 Publisher has in the works, one of which is an official EDF 4. We don't know what EDF 4 will include, all we know is that it's in development and it's a separate thing from Armageddon.
As well as that, we also have Earth Defense Force 2 Portable coming to the PSP, and Earth Defense Force Legend for mobile phones. The latter will come out first, releasing in Japan next month.
Typical. You wait ages for a new Earth Defense Force and four come along at once.
Yes, Earth Defense Force 4 Is In Development Too [Siliconera]