Wikipedia, a free encyclopedia, has an entry about the original control-flow patterns.
A workflow course based on the workflow book of MIT Press
A website on process mining

YAWL (Yet Another Workflow Language)
A workflow language/system based on the patterns

Service Interaction Patterns
A collection of patterns that can be used in service choreographies.

Patterns for Enterprise Application Integration
A collection of message-driven application integration patterns complementary to the workflow patterns

Patterns home page
Source for information about all aspects of software patterns and pattern languages

Proceedings of BPM 2003 published by Springer as volume 2678 of Lecture Notes in Computer Science and the edited book Business Process Management published as volume 1806 in the same series. If you have sufficient access to the Springer site, you can find the full papers there

Research at PADS Group - RWTH Aachen University

BPM group at QUT

See Vendors for links to systems