Codemasters has clarified to Eurogamer that all new Overlord games will be released on 26th June.
That includes Overlord II on PC, PS3 and Xbox 360, as well as Overlord: Dark Legend on Wii and Overlord: Minions on DS.
We've just this minute published a preview of the latter two. You might like to read it.
The Overlord series follows the eponymous anti-hero as he directs his minion army through do-gooder lands, either enslaving or destroying them - each path offering unique advantages. Importantly, though, there is no good option.