Today I was given the preview version of Mac OS X 10.6 (due for release in about 3 months). I've installed it and it's working well so far and seems to be a tad quicker which is nice. Includes the new version of Safari wit the 'Top Sites' feature which might be enough to convince me to switch over to Safari (I currently use 'Camino' for web browsing). I expect that BWT will occupy the top left spot in the automatically generated 'Top Sites' view, for me.
The built in Exchange integration looks like it's going to be easier to use on the Mac than on Windows (eg, doesn't require any additional software installed, and very simple to use - integrates with the included Mail, iCal and Address Book apps).
Most of the other changes are under-the-hood changes for developers (which will hopefully produce better applications for users in the long run).
However, it only runs on Intel Macs, so if you've got a very old Mac, then you're out of luck.
