I would have to disagree and say that this symbol is over-used and is only commonly understood by an audience involved in technology. If this is the case, another way of showing "control" or "start" could be developed. In this sense and design usage, it is something that is becoming a universal generic symbol and does not separate or create an existence of identity for the product itself.

Shawn - while I agree it could be interpreted as a niche reference to the techy crowd, something akin to visual jargon, I think that the symbol is far more pervasive in society as one of power through the prevalence of personal computing, and electronics in general. Furthermore the symbol, stripped of its original context, reads as a sexual one, the phallic "on" staff and the yonic "off" circle – both interlocked in this instance as one visual combination. In other words, the visual symbol takes on new, and appropriate, meaning in its new context and carries with it the weight and importance of its former context as well: power, control, and implied responsibility. Such re-appropriation is the very basis for all effective visual communication.