The Asterisk development team has released versions 1.6.0-beta2 and and 1.4.18-rc1.

The new beta for 1.6 is available for download from http://downloads.digium.com/.  The release candidate for 1.4.18 is only available via svn.  It is available for anyone that would like to help test 1.4.18 over the next couple of days before it gets officially released.