If he has a manual transmission in his car and yours is an automatic: offer to trade him - my sister did this for me when my shoulder was worked on, and it was a lifesaver. Had that not happened I would have either been fairly dangerous trying to drive one armed, or I would have been exceedingly grumpy never being able to leave the house, or being dependent on others to leave.
Don't mistakenly ask him to "carry this 70lb box of junk to the garbage" or "open this welded shut jar of mayonnaise" or other tasks that may end up straining the shoulder - the problem with these things is that it will feel fine right up until the moment it gives out and results in more damage. This is especially true in the beginning, if he tries to go beyond the doctor's imposed limits, he will probably be able to, but the problem is that you go directly from "I can easily lift more" to crying like a baby because "that was too much" - there is absolutely nothing to warn you of the threshold until you're already past it.
Lastly, walk the fine line between being too helpful and not helpful enough. If he makes a move to do something on his own, let him do it, don't offer to "help" or get whatever it is every time he stirs. At the same time, understand that just because you've seen him doing some things for himself does not that he's ready and capable of doing everything for himself. A lot of times we will push ourselves to a point, and know that we shouldn't do anything more that day. Other times we are lazy and just want you to do it for once
All of that being said, just keep in mind that shoulder surgery is one of the most painful procedures to undergo - for the first 24 to 36 hours, if he's not woozy from painkillers, he's hurting pretty badly, and will probably be very short and rude with you (and everyone else) - don't take it personally.
And my traditional ski bum comment: if it's his dominant hand, he won't be able to have as many happy endings during the week as he is used to - you should give him a hand with that...