The current official release of VERGE is always linked at the top of the sidebar, under 'Current Engine'.
All Work In Progress (WIP) builds of verge 3's engine are available straight from The Man at http://vecna.verge-rpg.com/verge.exe. Note that the WIP build is *not* documented and/or supported by the non-vecna members of the dev team. Heck, what's in there is quite often a mystery to us, too! ;)