works pretty well for me. The results are pessimistic that means it rather reports to few java installations than to much (http://java.com/js/deployJava.js see first function for details).
it reports java: x.x.0 for version < 6u10
and full version strings java: x.x.x_x for version >= 6u10
I guess you all know what you have to do now ;D
hehe that’s great 
note: I found that google analityc usually produce a little hang on page using it wich is annoying 
just put the google code snippets to the bottom of your page right before the
</body>
tag, this should solve the problem.
already the case where i used it, I have seen the problem in several website including well know websites : in the statubar for some few seconds there is sometime a message like “downloading from google analytics”, may be the analityc server is sometime too much used