I only have the Finder, 6 programs, and 3 folders in my dock. Not sure why one would want to clutter it up?
I've never heard of an upper bound being hit. I'd assume it's basically more than you'd ever use.
My MacBook Air currently holds 29 items in the dock and can very easily hold many more. I don't think there is a limit, and if there is, its probably no more apps than you have on your Mac.So how many icons can the dock actually hold?