[via Lessig, 1] Lessig reported, that people taking pictures inside Starbucks stores have been strictly advised by the managers to suppress those actions; also see the comments [2].
It is not that uncommon that one is not allowed to take pictures inside a building; you probably won\’t wonder if they told you inside a bank, a museum or at a shopping mall. There might be security reasons, copyright reasons or simply to let others feeling comfortable at that place. So that is not restricted to Starbucks; it is probably just a question of how one communicates the corporates policy.
[1] http://cyberlaw.stanford.edu/lessig/blog/archives/2003_05.shtml#001223
[2] http://cyberlaw.stanford.edu/mt/mt-comments.cgi?entry_id=1223
