The JavaScript/REST APIs have been generating lots of buzz, but I think the (really) new Flex API is awesome too and will garner lots of attention at ESRI’s International User Conference next week. Check out the samples:

http://resources.esri.com/arcgisserver/apis/flex/index.cfm?fa=samples

ESRI has clearly been hard at work on this, and it seems pretty slick. I can't say for sure yet, but I'd guess that a lot of the work that was put into ArcWeb Services was leveraged, and it appears to offer most of the functionality needed to build a basic site with Flash.

We’re doing plenty of work to incorporate emerging technologies like this into Geocortex Essentials in an agnostic way, but for 2.0 we’d planned to concentrate on leveraging the heck out of the JavaScript/REST APIs alongside Web ADF. But the more I play with this, the more I want to cover the Flex API right away too. It’ll be interesting to see how people react to this next week; this will help guide our decision.