Aside: someone should write a WINE-based wrapper of some sort for running Windows VST plugins under Linux and interfacing them with Linux audio software. It shouldn't be too hard; one way would be to write a very simple Windows VST host which takes audio input, runs it through a plugin rack, and sends it to output, and then use WINE to wrap it in such a way that the input and output goes to FIFOs in /tmp or somesuch. A better alternative would be to actually wrap the plugins within the host application, giving them just enough Windows GDI calls to draw their user interfaces and such. (After all, the DSP code should be fairly portable.)
It looks to do the same thing as plugin~.
I couldn't get a single sound out of PD when I tried it. But they should start making VST plugins available for Linux - after all, they're available for Windows and Mac. It should just be a matter of the developers compiling them as a .so instead of as a .dll, and having software that can access the API. As usual, Linux is about 5 years behind in audio software....
It's not that easy. Steinberg refused to allow an open-source port of the (freely downloadable) VST SDK, which is why we have LADSPA (which is a pretty daft name, btw; it sounds like a paedophile group or something).
http://www.notam02.no/arkiv/src/k_vst~-0.2.3.tar.gz