It does seem that active development and support by the Mono project team continues for VB.NET. The (draft) release notes for the next release, 2.10, includes an item regarding the VB compiler which is listed as one of the release's major highlights:
VB Compiler
The VB Compiler (vbnc) has been
upgraded to use cecil/light instead of
Reflection, which makes it possible to
create assemblies with different
runtime versions using only 1
compiler. That is very similar to the
changes that we did to the Mono C#
Compiler detailed above.
By default vbnc will now compile to
the 4.0 profile, and a new script
(vbnc2) has been added to compile to
the 2.0 profile.
