For along time there's been a significant gap in the perf and cap planning guides around the InfoPath Forms Services features of MOSS. I'm very pleased to see this gap now filled with the below recent publication. Essential for those architect-ing MOSS Enterprise deployments:
This performance and capacity planning scenario incorporates a single Microsoft Office SharePoint Server 2007 farm that is running InfoPath Forms Services
Estimate performance and capacity requirements for InfoPath Forms Services environments (Office SharePoint Server)
I finally got around to updating my list of post SP1 fixes, which is now fully up to date. Well until they make some more that is!