Paul Stoffregen has provided an update to the Entropy library that allows it to work on the ARM chip he uses for his Teensy 3.1 boards and is also producing test data for a couple of scenarios, the first of which has been posted to the wiki page. It is possible that this will also work on other ARM based arduinos but that will require folks to try the library and test it.
If you choose to test this on an ARM board (or another AVR) just load this sketch to the board and capture the output to a text file for at least 12-24 hours. Then send me the output file along with information on the board, the cpu type, its date code, etc... You can see examples of the information I need for each test (less the analysis which I will perform) on the wiki page for the library:http://code.google.com/p/avr-hardware-random-number-generation/wiki/WikiAVRentropy
Google Code has implemented a change that prevents me from placing a zip file containing the library on the sites Download page; however, I have placed such a zip file on a Google Drive and it is linked from the wiki page. You can also obtain the library by using the more traditional google code interface (git, svn, etc...)...