Adobe to open-source Flex

The problem with OpenLaszlo is exactly the fact that it supports both flash and ajax, and therefore it settles to the lowest common denominator of both platforms. Flex has richer components because it settles on only one technology (Flash) and therefore it leverages Flash to its full capabilities.

Another advantage of Flex over OpenLaszlo is the Flex IDE (aka Flex Builder). It's a great product! (Note: Flex Builder is closed-source, and a bit expensive -- $500 I believe)

Despite the fact that Flex is Flash-only, I think they did a great job integrating it to the web stack. For example, Flex uses CSS to define the component styles. ActionScript also feels pretty much like Javascript. As a matter of fact, when I started using Flex I had no Flash experience whatsoever and was up-and-running very quickly.