The price drop for PS2 may not be related to a PS3 release, but an effort to increase game console penetration. I'm no expert on the game industry, but my guess is that, like ink cartridges, games generate a greater source of recurring revenue than the hardware. Since PS2 (and Xbox and Gamecube, for that matter) are duking it out in a hyper competitive market, and the bloom has come off the rose since these consoles were introduced, this may be an effor to jumpstart demand, increase the installed base and raise longer-term game revenue. Also, I just read today that Sony recently reported disappointing earnings that has surprised many analysts, and they are facing a long term debt review (and possible downgrade), the first since 1989.
Bundling games and hardware, like has been happening recently, will only stimulate demand for so long and a hardware price drop is probably warranted to keep the pace going. The timing is probably good, because my guess is that console demand slows in the summer, and of couse, booms again near the end of the year. Drop the price now and they could get a substantial lift to carry them to Christmas. Then all those new console owners will be out throwing down cash on a truckload of new games.