Adobe recently announced that the new version of Flash will not support development in Actionscript 2. The Flash runtimes would be able to run old flash files developed with AS2 and continue to support it. With Actionscript 3 closing to its 7th year, the development in AS2 has considerably decreased.
With the advancement of AIR Mobile Apps and Stage 3D the move looks to be a sensible one. Still through the older versions of Flash, developer would be able to use AS2 still it phases out completely. With this announcement Adobe is giving a chance to the developers who are still on AS2 to move on to A3.