VHBL is a PSP homebrew loader for the Playstation Vita, a tool that allows you to run PSP homebrews inside the PS Vita’s playstation emulator. VHBL has the particularity to only require a psp user mode exploit to run, and was designed to be as easy as possible to port, but its low entry bar also comes with limitations (it will only run psp homebrews, not plugins or isos).
The Z had announced a few weeks ago that he has a running port of VHBL, and he confirmed recently that his port is complete, and could be released any time soon.
Sadly, the PSP game he uses as a vector for his exploit is only available in EU stores (and Australia), in particular it is not available in the US or in JP. This means that only people with an account in a European location would be able to use this exploit. It’s relatively easy to set up an account in another location and to buy PSN credits, but Sony has made it a pain to switch between accounts on the Vita.
The Z announced he would probably release his port for a future Vita firmware (not 2.1x), depending on the importance of releasing a VHBL port at the time (which I understand as: if something better comes up, such as a new release of CEF, he will probably not bother)