Lot's of talk today about a rumored big Sony announcement tomorrow. Tracing the source-chain backwards, it seems the rumors started at Australian site Smarthouse, which itself references Bloomberg, though I was unable to find confirmation of anything at bloomberg.com.
Everyone seems to agree the announcement has to do with the Playstation brand, but from there all bets are off. The most ambitious claims are for a $100 price reduction on the Playstation 3, a reduction on the Playstation 2 price to $99 (a reduction many feel is long overdue), and full PS2 backwards compatibility for the PS3, via software (the Playstation 3 originally shipped with full PS2 backwards compatibility in hardware, then reduced that to partial backwards compatibility via a software/hardware mix, and finally dropped it altogether).
Other possibilities are announcement of the Playstation Portable 2, or a price drop for the current PSP.
All of this is very much speculation and rumor. Joystiq turned up some good evidence of the PS2 price cut via a tip from a KMart employee. That might be the whole story, or just part of it. I guess we'll know for sure tomorrow!
[Update: Game journalist Geoff Keighley says Sony has sent out a press release saying they have no plans for a PS3 price drop. ]