i searched yesterday morning at activeden.net ... nothing ... they have a flex section
here at least is an AS3 flash version
my review of anything i have seen is yikes. even the demo of the above, it took a few passes at it to realize i was in a blog with its super narrow scrollbar.
there are some references out there of people pondering it. deeplinking is always an issue and people making shadow sites. and comments from purchasers of flash ones with missing functionality like categories, searching etc
my recommendation is stay away from the idea but that is my meaningless 2 cents
Anyway, technically it's possible to do this, but it's not a popular practice and I wouldn't recommend it. Mainly because it's not needed, IMO (nor is a heavily Ajax based blog a good idea, for many of the same reasons). What might make sense would be a traditional blog with a Flex comment submission section (not comments themselves--you want those indexed in HTML), but even then, unless you're after some feature that doesn't currently exist... I can't think of a reason to do it. Flex provides better return when used for web applications, not web sites.