The iMac (visible at 57 seconds) is clearly displaying the Calendar app, although events on the display are not visible. It is also clearly sporting an Apple-esque logo , and Apple keyboard (although the mouse appears to be a third-party substitute).
Note: several readers have informed us that Rockstar has used a bowl of fruit and the brand iFruit instead of an Apple logo in its games.
The Grand Theft Auto games are known for their ultra realistic settings, and the new game is unlikely to disappoint fans of the series, they often rely on copying real-world products, often with humorous names.
See also: Desktop Mac reviews
The computer is clearly an iMac, but it is unlikely to have been officially sanctioned by Apple. We're not sure if Apple would want to be associated with the trailer, which contains multiple shootings, an arson attack, and a violent bar fight. The trailer is marked "Grand Theft Auto V - ESRB Rating Pending: May contain content inappropriate for children. Visit www.esrb.org for rating information."
Grand Theft Auto 5 is due to be released in Spring 2013. It will be interesting to see if they include iFruit-themed Apple Stores in the game, or whether Apple requests to have its products removed.