Update 2009/08/19: Apparently the newly redesigned http://www.itanalystreports.com/ no longer provides the link to the 6/07 Gartner update mentioned below.
However, an excellent post entitled Project Management Online for Small Teams does provide a link. That article is well worth reading in any case and highly recommended :)
31July2007: Thanks to itanalystreports.com , an update from similar Gartner Magic Quadrant last year regarding the PPM vendor space:
"Gartner Magic Quadrant for IT Project and Portfolio Management, 2007 - June 2007, 11 pages"