I have worked with Viola-Jones before - it is extremely robust to lighting conditions. However what it is not robust to is angular changes (twisting of face sideways). It is possible that HP are using some kind of naiive algorithm to achieve face tracking, an easy one for e.g. is simple edge analysis for eye recognition (easier if you have a infrared emitter - to exploit the red eye effect) and then using this extrapolate facial dimensions then to facilitate tracking. It is possible they use Viola-Jones for the initial stage to locate the face region and then begin tracking, so even though the VJ tracker is very good, the processing further in the chain isn't so robust. Part of the reason for doing this might be that the VJ tracker is expensive in terms of compute cycles.
The only problem with X forwarding is, if the xserver dies, i.e. your netbook, then the whole workspace dies, the other option is to use some form of xproxy like nx.
This reminded me of an anarchy cookbook/manual I was reading at one time. One of the methods was biological warfare, where you would start off with a brew of relatively harmless bacteria and then start introducing anti-disinfectants to weed out the bacteria that were the strongest and then grow those - one would repeat this process until they were confident enough that when another person (possibly an enemy) when exposed would become either severely ill or die as a result.
over 9000 cpus!!!!!! in all seriousness, this get used so many times, especially by people who use scripting languages (e.g. python/perl/php/ruby/javapoo/next fad)
... who cares if the run time runs like sticky poo down the toilet, just throw more hardware at it.
This could actually work rather well and would require far less infrastructure to do it.
fork rtfa, thats for forkers. mysql is fail
... surprised it has survived this long, its basically sqlite with a server.