On my team, after experiencing a few competitions last year where people were very fond of their gameboys, we put a no games rule for the pits and stands. In the stands you are there for two main things; scouting and cheering. If you aren't doing either than you best find something productive to do.
In the pits we have an even stricter rule of no electronics (besides the robot of course

). The only laptop we have is the scouting laptops, and besides that the only electronics we may have is a phone.
The reason we don't completely ban phones is because they simply haven't been an issue. The majority of team members at an event are there for the competition, and do not feel like texting persons while there. If a text is to be sent it is to be done discretely.
So far I have not seen any phones or other electronics this year
Although this policy may change after seeing my drivers out on the field right before a match
texting!