I see now that Sony is developing some cameras that use compact flash recording abilities. What are the chief differences in performance, durability, etc between P2 and CF?

My non-scientific reply is "the same but different". I think it's just another way to skin the cat, still semi-proprietary (read, not "commodity" memory), slightly cheaper at this point. I wouldn't base my decision on these two approaches to data storage.

My non-scientific reply is "the same but different". .........slightly cheaper at this point.
"Slightly cheaper"!? I think that's a bit of an understatement! Or are you confusing Compact Flash with SxS?

I can get a 16GB Compact Flash card for under £150 - a 16GB P2 card is nearer £600! (UK prices.)

That said, the performances are very different as well. A P2 card is rated at 640 Mbs (80MBs) against 160 Mbs (20MBs) for the card I referred to - though both are more than fast enough to record a 100Mbs stream as used by DVCProHD etc. (Infinity uses CF and records 100Mbs JPEG2000 to such a card very well, apparently.)

A potential advantage to CF is that it comes in a variety of speeds/prices - pay more money, get better performance - whereas with P2 you HAVE to pay top money (and get top performance), even if the lower cost/performance option may be more suitable. (It's on this subject that there is a debate around SxS - will there be cheaper/slower cards for the EX?)

As example, the CF cards needed by Red need higher performance than the one I referred to, and are therefore higher priced. (Though still cheaper than P2, Gigabyte for Gigabyte.)

Yeah, I was referring to Sony's SxxS-whatever flash media.

Anybody ever try plugging a "fast" CF into a CompactFlash PC Card Adapter into the HVX?

P2 is not just memory. There are RAID controllers in the cards as well as four zero-defect SD cards. Simply plugging in memory that fits the form factor (CF card in an adapter) will not work.