One of my colleagues, Rob Collie, has created a new FAQ for PowerPivot @ http://powerpivotfaq.com/.We will try to answer as much of the questions on PowerPivot as possible. This can only be achieved because of the great volunteers who moderate this list of course.
More information can be found @ http://powerpivotpro.com/2010/01/01/the-great-powerpivot-faq/.
This also means that if you have a question on PowerPivot you are free to let us know. You can comment on the original post or send me a message through the contact form on this blog.
Happy PowerPivoting ;-)