Version 2.51 is the latest one, so the 2005 is correct. There's been no new version for WinSPMBT since then as almost all attention has gone to WinSPWW2 for most of the last year. But many of the new features and improvements made/found for WinSPWW2 will find their way into a new WinSPMBT version which is planned for the late fall/early winter.
Right now it's break time though as the development of both games was back to back. And it's summer!!!!
Narwan