Sony do have the rights to some sort of emulation software.
But, given for instance that the older 80GB with 4 usb ports, had software emulator but needed some hardware in it as well to play PS2 games, and even then it was only 75-80% BC, it doesn't seem likely that a 100% software based emulator would allow non-bc PS3's to play PS2 discs.
I do agree that Sony must be trying to make it work so that they can put some PS2 games on PSN for download, they'd make a lot of money out of them, but I think in order to make them work with the emulator they would probably have to update the games themselves as well when they put them in digital form.
So, the answer is, we really don't know what Sony are doing, or how successful they have been so far at making a software emulator work, but my feeling is, that if they do it, it will mean that there will be some PS2 games on PSN for download that all PS3's will be able to play, but that it won't allow non-bc PS3's to play old PS2 game discs.
When Sony said that they would not make another backwards compatible PS3, they may have meant that they will not be making another one that contains emulation or PS2 hardware in the console it's self, but that does not rule out a software emulator of the type I mentioned above, but as I said, it will probably be limited to a few downloadable PS2 games only, if they can get it to work at all:)