23" Acer T232HL works without issues with Windows 8.x and Ubuntu 14.04 -- but not with the latest-and-greatest stable release, OS X Mavericks.
OS X Mavericks recognizes it, but first few touches always go to upper-left corner (coordinates 0,0) and are interpreted as a click. Only third or fourth touch goes to the proper place -- but at that time it's already in the "click" phase, so the touch gets interpreted as a drag. It also gets recognized as a graphics tablet (Ink icon appears in System Preferences), but other than that, touchscreen is fairly useless with OS X.
Which is a shame, as its usefulness would be a middle ground between usability under Windows and Linux.
All this happens with a monitor that, to the best of my knowledge, represents itself as a standard USB HID device.
Hence, despite what other answers claim, I'd say multitouch screen support on OS X is incomplete and broken. Drawing conclusions based on multitouch touchpads or singletouch screens or singletouch graphics tablets is silly and incorrect.
There are some third-party commercial drivers that perform some magic to get multitouch screens into a usable state. Since the question was presumably about the stock OS, discussing them is out of scope for this answer.