If you have questions about what the PS3 is, why it’s built like it is, or where you can expect it to go in the future, then you’re in luck.  Apparently, Sony’s official, internal Q&A for E3 has leaked to the public, detailing everything from future plans for the console, to a justification of the employment of their Blue-Ray Disc technology.  A few key points are that:

PS3 is being positioned as a computer system, and not a computer entertainment system. Like other computer systems, it can be upgraded through the use of readily available industry standard adaptors.
There will therefore be two initial configurations of PS3, not two versions.
With the exception of the HDMI socket, every aspect of the 20GB model can be upgraded using readily available, industry standard adaptors.
No SCEE decision has yet been taken on the splut of PS3 configurations for the SCEE market.

You can peruse the full E3 Q&A at your leisure here.