No doubt you heard the Lp & Jay-Z collab in 04...well following on from that i'm guessing that Mike Shinoda had quite a bit of contact with Jay-Z and basically started his own hip-hop project named Fort Minor. As far as I know, he is the only member of Linkin Park in the collective...I hesitate to use the term "group" as it brings up horrible pop connotations! The rest of FM is Apathy, Styles Of Beyond, Ryu and a few other guest appearances by the likes of Common.
As well as starting up Fort Minor, he also has his own label, whether it's all his or a sub-label on a bigger company, i'm not sure...but it's called Machine Shop...you'll hear it name checked on a few FM songs.
In regards to where he stands with LP...there has been no real comment, I can't imagine he'd leave the group as LP are one of the most original rock groups of recent years, i'm a real hip-hop head and they make rock music even I can listen to...but that's probably down to the huge hip-hop influence that Shinoda added to the group.
Although i've already said it, I can't stress enough to check out Apathy's album, i've been hammering it for weeks now...easily as good as FM!