One would have to be a spectacularly unaware competitive cyclist to remain ignorant of the spread of power meters in the ranks of bike racers. In the past I’ve not moved in this direction, for a number of reasons, some practical (e.g. typical power meters would be a faff to move from bike to bike, unlike the typical HRM), some more theoretical ( e.g. isn’t it best to assess the physiological demands of a training session).
At the end of the 2009 season I bought a Polar CS600X bike computer with power metering capability. I’ve written the first part of a review on the usage of power meter data (framed by a book review) over at the Team Grumpy website.