Reputation is meant to be earned, not given. So if you're knowingly posting a question, having a friend answer it, and giving him a bounty to give him a boost on his new account, I believe this to be against the rules. You might get away with a couple of times, but soon enough someone will notice.
By making a user earn reputation, StackOverflow limits the speed with which they gain privileges, forcing them to learn about the StackOverflow Q&A model and how it differs from traditional forums.
Giving a user a direct 500 rep boost will grant them more than half of all privileges almost instantly. Such a user will then be able to comment, retag questions, flag, vote up and down, create chat rooms, set bounties, edit Community Wiki posts, and close their own questions, without really having learnt what each of these means and what the consequences are.