- February 2003: Six Apart announces Movable Type Pro
- August 2008: Movable Type Pro ships
5 1/2 years - not bad!
Kidding aside, I will upgrade to the final version of Movable Type 4.2 very soon (since the release candidates rocked hard) but will probably pass on MT Pro as its social features are overkill for a site like this, which has recently gone for whole weeks with no comments. Admittedly there have also been weeks without entries too...
I am pleased that MT Pro is being released as a free (as in beer) upgrade as it essentially replaces the previously paid-for Movable Type Community Solution, and it makes MT stand out more over Wordpress, which would probably need all manner of plugins to match MT Pro's full functionality.

You forgot to mention the biggest news of all… OMFG, THEY ACTUALLY BOTHERED TO WRITE DOCUMENTATION FOR THE TEMPLATE TAGS!! Pretty crappy documentation with very few contextual examples of usage, but still…