ESB or BPEL?

Yet another interesting question I tend to get asked about almost in every SOA panel. There are many flows that can be implemented as mediations (ESB) as well as BPEL (BPM).
Almost all vendors bundle ESB and BPEL engines in same product edition which allows even better flexibility to the architect / designer to decide which technology to use for the implementation.
Examining the SOA architecture, it is quite clear that BPM and ESB are there for very different needs - BPM for the business processes requiring analysts to model and business owners to monitor, while ESB for integration specialists to mitigate protocols, models and technologies.
Marc Fasbinder, BPM Integration Solution Architect, IBM, gave a nice summary of features and differences between BPEL and ESB which gives some key directions in choosing the correct technology for each flow.