What BPM tools are compatible with Presto and are there any cloud based BPM?

Most BPM and BPEL based systems expose the processes as WSDL services.  So we would interface at a data standards level (RSS, ATOM, REST, SOAP).  Most BPM tools use these standards today.  I recommend looking at Forrester's research on the BPM market for good cloud BPM vendors.