I have received some product information from Nyko, maker of accessories for the PSP, that contains details of two new products they are just releasing. The cooler of the two is the Nyko Theater Experience for PSP that is basically a protective aluminun case that acts as a stand for the PSP, provides up to 5 hours of playtime via the integrated LI battery, and offers "theater-like" sound through the two attached speakers. The suggested price is $80 with availability in the summer of 2005.
The other product they were pitching to me is the Charger Case for PSP which adds up to 7 hours of additional playtime. The Charger Case is an aluminum case that contains a battery and will recharge the PSP directly from the case. While plugged in the case will always recharge the PSP first and then the case battery, and it always uses the case battery first during gameplay so the PSP charge is not depleted. The suggested price for the Charge Case for PSP is $70 and should be available soon.
UPDATE: Nyko has sent me some additional information- the MSRP for the Charger Case is now $59.99 and both accessories are now available at major retailers (Best Buy, EB Games, etc.)