When I Googled "UML Certification" I only found two organizations offering certification. The rest of the sites were either just talking about UML certification or were, like Whizlabs, offering
test study aids.
Besides the IBM certification exam the only other one I found was the certification from the Object Management Group (OMG). Since OMG is the organization that maintains the UML standards, thier certification is certainly nothing to sneeze at.
That said, the IBM exam is perhaps better known than the OMG and the IBM exam is just one of many certification exams and programs from IBM.
[ April 11, 2006: Message edited by: Linda Walters ]