I always prefer to eat at places that do this, the down side is if the server sucks the other people get shafted out of their tip. Luckily, when it's pooled like that, the servers are rarely bad. Probably because the mean old cook and the huge bartender would kick their arse.
It's pretty common. A lot of servers also split their own tips with the hostess (for filling their areas and sending them people who "look" like good tippers) and busboys for clearing the tables for the hostess to seat more people in your area.