Update Punishment

I would tell him that having friends over means he is a "host" and having guests in your house means responsibility, and having respect. He should be appriciative that you allowed his friends to come over, and you do this cause you know what a great time they will have. However, they cant stay forever and in order for him to show appriciation for you allowing them over, then he needs to not give you a hard time about when they have to leave or next time you will have to say no, or think long and hard about it if he cant understand that. Moms have to be moms, and you sound very good about the friend thing.

I am shocked at some of the commenters so far saying it is "normal" and acceptable for a 9 year old to throw a fit. Being disrespectful is never OK. I expect a two year old to throw fits - and be punished for them - but by 9 it should not be the norm and good for you being a parent and teaching him he needs to learn to control his emotions and show respect for others. Too many parents let their children express themselves freely without teaching them to respect others and have a little self control. Stay firm and assign more chores if he keeps acting up and don't forget to sit him down and really talk to him about why he was wrong and what you expect of him at his age. He should not be allowed to treat anyone like that.

My daughter did something similar last weekend.
I believe more in natural consequences than in punishment, so I told her, because of your behavior we won't be doing anymore sleepovers for a while.
When the consequence is directly related to the offending behavior I find it to be much more effective!

It's hard for little people to handle disappointment, the fun ending and thinking like a mature adult.

The best thing to do is explain to him after everybody left that while you understand he was disappointed, he can't handle it that way. Then you should have made the punishment then commensurate w/the offense.
Meaning it was a small offense so punishing him ALL day might be a bit heavy. A better thing may have been to restrict him from tv for an hour RIGHT AFTER it happened or something just like that.

Also, there's no offense in grumping if he's doing the work.
It's like us grumling about taxes but we pay it.
Or grumbling about the rising cost of gas but we still fuel up and drive.

I would have let it go, but the next time he asked to have friends over, I would say no because of the fit you threw last time when it was time for them to go home. Logical consequences.

Keep the lines of communication open. He needs to understand what he did and why he is facing conquences.

Next time give him fair warning, Honey in a half hour it will be time for your friends to go home, then 15, 10, he will understand that it's time to say good night. Assure him he can have them over again soon.