Man, this sounds too familiar.
We left the majority of our gear at our campsite in 'Little Yosemite Valley' but like everyone's stated above, as long as there's no camping, you're fine.
We were up there from 6PM to about 11AM the following day. We didn't sleep, but we ate food occasionally and looked up at the stars while we watched our timelapses finish. We had our sleeping bags--just in case--it got too cold, but at some point I even took off my jacket because it was so nice. When you get shots like this, its totally worth it:
We were up on the summit of half-dome alone for about 12 hours. It wasn't until sunrise we actually had some visitors. However we later had a ranger come up the cables because there was a death from a climber who fell when reaching for the 7th pitch on the north visor--which Colin and I witnessed, and had a radio to listen in on.
The chilling part is that same ranger--Ryan Hiller btw--that had us fill out a witness report, and tell him what all our camera gear was for--was killed a day after our Yosemite HD release. You can ready the story and see a photo with him(in August the day before we did our timelapses on half-dome) and us here: http://latimesblogs.latimes.com/lanow/20...ters-state.html
It gives me the chills thinking about it, but to keep it simple, if you ever plan on doing something like this, realize the risk and danger involved. Be aware of weather--we were up when we had clear skies for a whole weekend--and have plenty of water. Its kinda odd that no one caught on that we did this, but then again, I'm just now seeing this. Too funny.