reFX has updated Nexus2 to v2.5.9 and announced that Vanguard2 is in development.
Vanguard2 will be 64-bit, fully backwards-compatible with Vanguard, and will be provided, upon release, as a free upgrade for all owners of a Vanguard license. No release date has been set.
The Nexus 2.5.9 update provides a few bug fixes, and is required for some newer expansions.