There's currently a lot of discussion about common VMs for multiple high-level languages. However, what I want to do most of the time is use a Perl module from Python or vica versa, so a simple bridge between those two languages would suffice, and would save having to reimplement both languages.
The idea would be to wrap functions from one in a reasonably clean way in the other. Since both are dynamic languages with roughly-comparable basic data types, this shouldn't be too difficult to design; the mechanics of having both VMs coexisting in a single process may be more involved, though.
This might end up like a more dynamic version of COM or IDL, with a common standard that could map to multiple languages.