I was thinking about all the aftermarket barrels available for different types of firearms and the lack of anything for the 15-22, does anyone else think that at least S&W could offer something. Would love to have the fluted barrel that's on the PC model, but just can't justify buying yet another 15-22 just for the looks of the barrel

Funny, you should mention it. I have looked around and the only way I can find to get a new barrel is have one custom made by one of the bigger barrel makers.
Its not an off the shelf pattern so it would have to be a custom one off thing and the some of the prices I saw quoted came close to or even exceeded the cost of a new rifle.
So I'm looking into giving the barrel to a talented machinist friend I know as well as an old 20" stainless steel target barrel I replaced in my !0/22T, and see if he can make a copy of the it using the longer 10/22's barrel as a blank.

I'm really interested to find out how that works for you, have a few extra 10/22 barrels around here, will have many questions for you. I hate to admit it but, I haven't taken a barrel off any of my 15-22's YET. I don't know how the 15-22 and the 10/22 barrels compare to each other as to how they each connect to the receiver. Got a shooy wrench on the way. (didn't see the need to remove the barrel on the 15-22's till now)

The 10/22 barrel is held in with a screwed in almost hook like piece underneath.
The 15-22 fits in from through the receiver from the rear with an over sized ring pinned to the chamber end. Then the ring nut gets screwed on to the barrel from the front sandwiching the receiver in between.
The Ruger barrel is a bit larger in diameter so there is enough extra metal to machine the threads and pin the chamber ring on.
If there is a fly in the ointment its the notch cut into the bottom of the Rugers barrel.
I am sure its not enough to maker any real difference to how well it can be held in. Otherwise an experienced machinist shouldn't have any trouble cutting threads with it there.

Have quite a few 10/22 barrels stuffed in the back of the gun cabinet, know how they attach, just wasn't sure how the 15-22 barrels attached

I only typed it all out like that in case you or anyone else reading this might not know.
BTY Not having one in hand to measure I'm not sure if a standard 10/22 can be redone to fit or not.
I have a T barrel (.920) from my 10/22T and know it has enough extra metal on it to do the machine work.