Its not super simple to run groovy on android yet but its certainly getting there. What you need is
this package and some patience. First of all edit the default.properties file so that sdk-folder points to your install if the android 1.1 sdk for example "sdk-folder=/home/hjalle/arbeten/gsoc/android-sdk-linux_x86-1.1_r1".
Now run "ant -lib ./libs/discobot.jar" from the command line to build the application this will result in a apk file in your projects bin directory.
Simply install it with the command "adb install bin/Hello-debug.apk" and run it from your emulator!
Theres a few caveats tho, this is a debuggy/hackish build of groovy so it spews out quite a bit of debug messages and theres no dynamic compilation yet.
If your interested in fiddling around a bit more you can download this tarfile which conatains a slightly more ambitious project. It is based on groovy 1.7 beta and contains a copy of that source tree inside the groovy-core folder. Inside the discobot-patches folder resides all the files that need to be modified for groovy to work on android.
And inside the libfolder there is a script called main.groovy that verfies all the patches (makes sure the original files have the correct CRC) and merges the two sourcetrees into the mixerfolder.
This is still a work in progress. Theres still no way of keeping track of which files belong to what fix but that is on the todo list along with moving as many of the patches as possible to retrotranslator.
And it doesnt run on android yet since groovy has evolved quite a bit since 1.6.3 and theres quite a few new problems to solve.
Note: Theres now a google code project @ http://code.google.com/p/discobot/ the files are downloadable from there aswell