From Yahoo! News
Flex 2 includes a number of free features, such as the Flex SDK (software development kit). The real changes, though, are in pricing, where Adobe is looking to reduce the cost of simple Flex deployments.
With Flex 2, Adobe is permitting free single CPU deployments of Flex applications using the Flex Data Services 2 Express or XML and Web Services. Previously, Flex users paid $15,000 per CPU to get started with the Flex SDK, which was part of the Flex Presentation Server.
Yikes! $15K? No wonder AJAX is winning out … be curious to see how things shake out with a more aggressive pricing model. Can’t really get more aggressive than open-source (free).