Why people have laptops
My local cinema, a Cineworld, has had notices up banning laptops and similar for many months now. As to why people would have them... well... next to the cinema there are 2 large universities within 5 minutes walking distance (one literally the next street along), along with at least two colleges. There are several other colleges and another University all within about 20 minutes walking/public transport.
I have seen plenty of students coming in the evenings after (I assume) being at college/University during the day, with their laptops etc..., and arguing with staff that it's unfair they can't get in. While many business people aren't likely to go straight to the cinema after work, for students that seems quite reasonable - and they likely don't have a car to stash them away in as someone suggested above.
I'm guessing students are a good part of the customer base of cinema's, and also from surveys, in the age group most likely to pirate and download films etc... I can't see how putting up barriers to them attending is going to help cinema attendance and reduce piracy.
The big question is - what is going to start happening with the 5"-7" tablets like the Dell streak, if/when they start gaining significant audio and video recording equipment? Where is the line going to be between a phone, tablet, laptop etc...?