Get your techie hat on; Sony has filed a patent for Emotion Engine (PS2's CPU) emulation tech for the PS3's Cell processor.
Techie jargon aside, that basically means Sony has the tech to make the PS3's microchips do what the PS2's brain does - i.e. play PS2 games. Which points to the possibility that PS2 backwards compatibility could be on its way back to PS3 soon.
Sony hasn't confirmed this, nor would it pass comment on the patents when we asked earlier today, but it's an encouraging sign.
Although PS3s currently on sale contain no support for PS2 games, the first PS3s released in Japan and the US in 2006 had both the Emotion Engine CPU and the PS2's graphics processor chips in them, allowing for full backwards compatibility with PS2 games.
The EE chip was later removed for the PAL (Euro) release of PS3 to cut costs, but early PAL PS3s still played most PS2 games using the remaining PS2 graphics chip and software emulation.
Hopefully the new patent means Sony will be able to re-introduce PS2 support using software emulation via a firmware update. Fingers crossed for version 3.0 then.