X-Men Movie Rights


Hey Scott, 
Saw this article about who owns the rights to what comic properties and wanted to get the comic readers on the blog's take on it:
http://uk.movies.yahoo.com/blogs/movie-editors/why-spider-man-avengers-never-team-112908050.html
My questions are:
Has it ever been established what X-Men, Fox has the rights to?  
If Marvel creates a mutant today (August 2012) does the movie rights go right to Fox?

Just wondering because there so so many mutants and I am sure Marvel themselves could make a movie using a secondary X team like X Force using mutants that Fox does not have.  

Fox clearly has the rights to Deadpool as well because they were going to make that movie before the deal fell apart.  Plus Blade and Punisher both reverted to Marvel recently.  So it's a big mess all around.    
The question of ownership of the X-Men is far too complicated for me to settle, and even the studios, apparently. I'm assuming that when they bought the movie rights it came with a big list of people they could use, because Hollywood tends to be specific with stuff like story elements and characters and who can use what.  For example, the original screenplay for Thunderball (the Bond movie in the 60s) actually ended up getting split off into two different movies because certain "elements" were owned by different people:  So we got Thunderball and then a couple of decades later, Never Say Never Again.  So I'm thinking any "new" X-Men would be owned by Marvel, but if they made a movie they couldn't call them an X-Man because Fox owns the rights to that name.