4.9.39 is available via the Beta button on either your Pro page or the bottom of the download page after going through the download steps at
http://www.limewire.com/english/content/download.shtml
LW has almost never announced a release date, because they don't know what will show up in beta testing and need fixing first.
The changelog at
http://www.limewire.com/english/cont..._history.shtml hasn't been active lately, but the key new development being tested in 4.9.39 is the junk filter. It's being discussed at
http://www.gnutellaforums.com/showth...threadid=49917