Along with this movie, imdb actually has a movie listed called Wolverine to be released in 2007. It simply says Wolverine continues the search for who he is and where he came from or whatever... Starring Hugh Jackman.
Apparently Wolverine and X-Men 2 are all produced by Hugh Jackman's production company.
I read he just set it up, and these are its first movies.
It is a great idea, and I hope they continue on with more X-Men flicks afterwards. Though if I remember correctly, they said something about it being a trilogy
"I'm for it so we can put Nuclear power plants up there, and then beam the power back to earth on a laser beam." ~ Whidden