Regarding the bug that there is a patch for - I was bitten by it too.
Quick fix: search for recepient [sic] and replace it with recipient
I think this is a very serious bug on a really excellent product because for me it meant that PP was essentially unusable. Notification of events is the single most important thing IMO in such a system. I'm wondering how many people have moved to Basecamp - as I was about to - because of this. And tracking down the patch was not easy in this forum !
It would probably be a good idea to apply that patch to the present download as it seems that bug has been in place for about 6 months now.
Otherwise, great job!