Sharp-eye observers perusing Sony's offical PlayStation 3 FAQ have noticed that the issue of using PSne and PS2 game saves on the PS3 has been addressed.
How can I save my PlayStation 2 memory card information to PlayStation 3?
To use saved data on a PlayStation 2 memory card, you must copy the data onto a virtual memory card within the hard disk. This requires a PS2/PSone memory card adaptor to copy the data to your PlayStation 3. A memory card adaptor is designed to edit, up/download game saves to and from EMS flash card or smart media card.
No mention was made of how much the memory card adaptor would cost, or who even would make it, but it's good to know that Sony plans on letting us use our old saves.