Well, I did a forum search and no luck. The WIKI functions list says "as of SL v 1.6 there is no 'Rotate Avatar' function. So my question is: What about now that we're up to v 1.10.2?
If there still isn't one, there really needs to be. It would simplify scripting short range TPs immensely so that the AV is facing the way you need them to after teleport. The current method is negated by the need to set Zero Rotation to simply get the TP to work in the first place. This requires either moving objects around to accomodate (which really screws with design plans) or just saying forget it and let the slopppy work stand. A 'Rotate Avatar' to set the AV facing your sign or etc, once they've arrived, would be terrific.