Here's the link to the latest Release Candidate. http://www.luxrender.net/en_GB/standalone

I usually have two Lux program files setup.  The current stable release and another for any Dev Builds that I want to try out.

As stated this IS a release candidate so no where near fully stable yet..Though I have been using it without any great issues...Just don't replace your current stable Version of Lux with it yet.

Cheers,

S.K.