Looks like it was just posted this evening. I had coincidentally decided to check to see if it had finally been released, and came across this lengthy forum thread of frustrated phone users where the release of the update was eventually discovered.
I haven’t installed it yet, but I’m curious about the changes and improvements that have been made. I’m hoping that Internet Explorer will be a bit more stable and capable — I’ve noticed that the version included in Windows Mobile 5 has issues with pages that use JavaScript and such, and my experience with Opera Mobile wasn’t much better. (And don’t even get me started on Minimo…)