WDWinfo.com has posted dates and times for the Pirates and Princesses Party:
DATES for the Pirate and Princess Party:
August 11, 15, 18, 21, 24, 28, 31 and September 3, 2007
Get ready for the return of this popular special ticket event at the Magic Kingdom. For 9 select nights starting on August 11, the “Pirate and Princess Party” will be held from 7:30pm to 12:30am.
(Shh, don’t tell my son . . . we’re going August 28 and he doesn’t know about the trip yet . . . )
Lots more detailed information about the party is on the WDWinfo page. We still await official confirmation on the Walt Disney World web site, but WDWinfo is a reliable source.
Broke Hoedown 
While I’m happy you will experience the P&P Party, I’d much rather it be held in the Jan-March time frame. I think having these sort of hard ticket events in the off-season could give others a reason to go.
Enjoy the firework show, though. Truly amazing! (And I;m still looking for source audio from it.)
I am definitely looking forward to those fireworks!
And hey, what a perfect excuse for me to link to the MouseGuest Weekly videocast of the Magic, Music, and Mayhem fireworks released last month.