Jason Langridge's post entitled "Windows Mobile Developer Exam is Live" made me check my MCP profile as I took the beta exam for "TS: Microsoft Windows Mobile 5.0 - Application Development" back in September 2006. I had almost forgotten that I took the exam as the beta period for the exam was extended so it took a long time for the exam to go live and for the results to be announced. The preparation guide for 70-540 can be found here.
Anyway, I have passed the exam and the new competency's fairly long name is making the MCTS logo look like this!

It was funny to see the press release for Windows Mobile 6 even before the developer exam for Windows Mobile 5.0 went live! The new "Technology Specialist" credential is designed to cater for such scenarios by specifying the specific technology area, which can cover various versions of the same product/technology like Windows Mobile.