The PS3 & Xbox360 have been on the market about 3-5 years. In that time, PC graphics cards have more than doubled the bandwidth, gpu performance & video memory-- while consoles have stagnated with the SAME essential equipment. There was also a boom bust and recovery (re-boom) cycle that's taken place in that time as well.
The gaming industry has enjoyed a virtually recssion proof history despite rampant piracy, the internet (forever expands the mode of gaming), recessions, controversial walled garden moves towards consoles and platform battles, etc. This pendulum that swings back & forth between consoles & PCs has been going on since the early 1980s (obviously, home computers weren't affordable & desirable machines until the later 1980s).
I will give credit to the gaming industry where it's due. AS A WHOLE, this industry is more receptive to it's target audience on what games get made and how they evolve into sequels, expansions, and updates, fixing problems. Try comparing that to other slow moving industries such as the music and movie industries (hollywood, and recording industries) and you will see a wide disparity between consumer, customer and end-user (taking piracy into account as well).
Oh yeah, one more thing.. eventually next generation consoles will steal the PC thunder-- but not for another year or two at least. The economic recession is taking a significant toll on consoles which until recently were vastly ovepriced.