Exactly, but I think they'll know that if they try to keep it off the internet, bootleggers will try their hardest to record it illegally and put it into the public domain. As a result, I'd expect an online release of the trailer at some point in the next few weeks, perhaps as soon as next week, but I'm obviously only speculating.
If it is playing before TDKR then we`ll be getting a trailer hopefully online right? Unless they don't want it online?
The main thing we need to find out first is whether this is intended only as an IMAX exclusive or whether it will ultimately gain general release as well.
I remember the Inception trailer was shown before Inglorious Basterds and didn't appear online for a week. I'm suspecting this could be the case with the IMAX Skyfall trailer.