O.k someone else who takes more notice than me will be able to give you a much better explanation but here goes. I read the Ultimate X-men book in the store but don't buy it, I buy Ultimates though. (obviously theres going to be Ult X-men spoilers people)
So anywho the whole world thought the X-men had joined Magneto's jolly crew so they went into hiding and the Ultimates came after them yadda yadda yadda. MEANWHILE over in Ult X-men Magneto had Forge build this huge 'dooms day weapon' which very creativley would amplify Magneto's power about a gagillion times or something.
So anyway Magneto's in his machine and the X-men turn up and beat his up old school then the government or someone drops a bomb on the place but Jean used her telekenis to protect them all from the blast. So somehow, I forget the details, Magneto sets of a nuke or something in Florida and Jean uses the Phoenix and the help of Professor X, one or two other X-men and some rewired Sentinals to save the day...and NightCrawler was there too I think.
Ahem, so now they've saved the easter sea board a whole bunch of humans are gathering round them but instead of throwing things like the X-folks expect they start cheering and the world loves the X-men.
So now Nick Fury has the X-men mansion rebuilt and the X-men are now funded by the government and they have a party with the Ultimates on a X-men parents day and Hank's parents are there being stupid and Tony Stark is chatting up Storm and Jean.
I think it ended there...Oh Xaiver hinted to Nick Fury that he might have planned the whole thing and then he called the cat 'Mystique'.
Hope that helps.
I liked it...Although the art by Chris Bachalo or whatever his name seems messy, I can't understand why they call him a 'fan favourite'.
Walla Walla Bing Bang.