The Skorpios project now has the latest code for my particle editor. Here is a JWS:
http://skorpios.googlecode.com/svn/jws/particleEditor.jnlp
A screenshot (click for full res):
http://n4te.com/temp/dragoneditor.png
You can also see some particle effects in action in my Dragon game preview.
The emitters are saved to a text file that should be easy for any language to parse. Since this is meant to run on Android, I tried to make the particle manipulation reasonably efficient. The rendering of the emitters is specific to Skorpios (works on desktop via LWJGL and also on Android), but could easily be made to work with libgdx, just LWJGL, could be integrated with Slick, ported to JOGL, or whatever. If people get interested this could become its own project, or get merged with other projects.