This probably really belongs on the message board (where I just put it), but I know some don't go there (why not?) Maybe someone already put it here and I missed it. Apologies if it's a duplicate...
Wendell Willick, the CEO at Point2 put a post about the Performance Index on his blog at:
http://www.wendellwillick.biz/2007/05/the_mighty_perf.html
Mods - if this needs to be deleted, go for it! I just wanted to make sure everyone had the opportunity to see it...
Enjoy!
JT