The current rumor is that sony plans on updating ps3's with "emotion emulation" technology. They recently filed a patent under this name. Seeing as the ps2 chip was called the emotion engine, we can assume that a downloadable backwards compatibility update is in the near future.
Also, knowing sony, they probably planned on having this patch out once the non-backwards compatible systems were the only option on the market, but took their sweet time to get it out (my sources say that their IT dept. doesn't have a lot of resources, so projects take a long time).
Edited, Aug 18th 2009 5:08pm by MerylStryfe
This is a common misconception.
The original NA and JP launch systems launched with full hardware compatibility. That is to say, they featured both the PS2's CPU and GPU physically within the system.
By the time of the PAL regions' launch and the introduction of the first 80GB SKU in NA, the PS2's CPU, dubbed the "Emotion Engine" had been eliminated from the system by way of emulation on the PS3's Cell processor. The GPU processor of the PS2, named the "Graphics Synthesizer" still was physically present within the systems to provide BC for the GPU portion of PS2 games. All subsequent versions of the PS3 (including the new Slim model) have shipped without either the CPU or GPU from the PS2, and have been thus far incapable of PS2 BC.
Earlier this year, Sony patented a new form of Emotion Engine (the PS2's cpu) emulation, and caused quite a stir online with hopes of a new patch to make the current models BC with the PS2 by way of a simple FW update. The obvious problem with the theory is that the PS2's CPU has been successfully emulated on the PS3 for years now already. The required emulation advance necessary is for the GPU, or Graphics Synthesizer, and no source has ever even intimated (let alone shown any evidence) that the GS has been successfully emulated on the PS3 hardware. In fact Sony not only denies that they are any longer researching fully software driven BC, but also has claimed repeatedly that it is not a feature requested often enough for them to consider.
Now I've seen Sony lie enough over the years to agree that not admitting research on BC doesn't necessarily mean they couldn't in fact be doing so. But I also have never seen any major company try to downplay the importance of a product they are spending money and resources on.
There might very well be a fully software driven version of PS2 BC one day on the PS3. I'm simply telling those thinking of making a purchase to not assume it's coming because of easily debunked internet hype.