IBM is the big dog in the BPMS landscape.  BPM 7.5 combines the old WebSphere Lombardi Edition and WebSphere Dynamic Process Edition (aka Process Server) in a single offering.  More than two separate products in a single box, there is real integration under the covers, in the form of a shared Process Center repository.  Find out all about it in my latest Industry Trend Report, available here.  You’ll need to be registered on BPMS Watch to access it.