Actually, I've heard through the grapevine that there has been some studio interference, but nothing too groundbreaking. The first bit was back in the summer when Fox did some budget cuts to the screenplay. It was around the time Matthew Vaughn did the interview citing that he saw and loved Inception, and had to cut some sequences because they were too similar.
Well, according to what I heard, that was a little misdirection on Vaughn's part. It's true that he loved Inception and that there were similar gravity-defying sequences, but he didn't want them cut, he was forced to cut them. Allegedly they were his favorite parts of the script. He was trying to fight to have them remain, and the interview was part of his ploy to convince Fox to keep the sequences, but last I heard they have remained cut.
Another recent dispute I've heard has been about the trailer, which might be a reason why we've had to wait so long. Apparently there is a cut of the trailer that exists out there, that was specially cut by Vaughn - that is suppose to be pretty unconventional, or so I've heard- but Fox wants another trailer that's more conventional and standard. We'll see who wins that battle.
Again, all of this is hearsay and rumors that I've heard, so take them all with a grain of salt for now.