They're blocking installs after August 15th, so if you want it, you'd better hurry. Though it isn't clear what happens if you've installed Flash previously, but not on the particular device you want it on.
In an update on its official blog, Adobe said that there will be no certified implementations of Flash Player for Android 4.1 and beginning August 15, it will start limiting access to updates to only users that have Flash Player installed.
From http://thenextweb.com/mobile/2012/06/29/abobe-pulls-support-...
(http://news.ycombinator.com/item?id=4175853)