Apparently someone on the Windows Mobile team (or one of Microsoft's partners) got a little itchy and has been leaking pre-release builds of Windows Mobile 6 (Crossbow) onto the internet. With a little googling and/or bittorrenting, you can be the proud owner of a 50~60MB install file to place on your own phone.
So what's changed?
And from the video, it doesn't seem like Crossbow's all THAT much faster than the Windows Mobile 5. Sure, there are some speed increases, but delays are still the name of the game. Let's hope there've been some tweaks between this release and the final.