I must confess that I haven't heard much about PerformancePoint Server 2007 beyond the fact that it was one of the several "Office 2007 Servers" that were mentioned in one of the books I already had listed on the SP 2007 book page because another of the products IT talked about was MOSS 2007.
(http://www.amazon.com/exec/obidos/ASIN/0672329492/heme0f)
But one of my RSS feeds gave me a post from Philo Janus talking about his new PerformancePoint Server 2007 book and I wondered why I had subscribed to blogs from him so I went to look at the book.
Then I found that this product works with MOSS 2007, so I checked out a few more of the PerformancePoint Server 2007 books' descriptions and found that they too mentioned SharePoint.
So I made the conclusion that listing books on PerformancePoint Server 2007 might well be a useful thing to have on my SP 2007 books page
(http://wss.asaris.de/sites/walsh/Lists/WSSv3%20FAQ/V%20Books.aspx)
and created a new Group for them, which now has five entries - three are out; one is out but available at the moment only from Amazon UK (which is unusual) and one (in fact, the Philo Janus one that started this whole thing off) is not yet out.