As smaller organizations, we do not have quite the same concerns in regards to personal technology and services in the workplace. That said, it would be shortsighted and potentially damaging to not at least give the issue some consideration.
Concerns might center on issues of productivity (too much Facebook usage), security (copying organizational documents onto personal, non-encrypted USB drives), or infrastructure (all those Pandora streams chew up bandwidth).
Coming up with hard and fast policies might be a bit daunting and in fact may be overkill. However, at a minimum, a general set of guidelines should be established and reviewed annually. This ensures that everyone knows the game plan, and provides a baseline for discussion, because the tools are gonna keep changing.