No, flash hasn't been improved. Swfdec compatibility will be more and more obsolete as time goes, since the project is dead.
The only area where it could improve a bit would be speed (recompiling it with more recent cairo/pixman versions, and possibly hw accel someday).
In the long term, as i think i already said a couple times, another candidate for Flash would be lightspark, or maybe even gnash if it gets significantly better than swfdec.
