Its interesting that Camomile and the updated pdvst were announced in these past weeks as I've been working on pdlv2, a wrapper/parser the generates lv2 plugins from pd patches.

https://github.com/x37v/pdLV2/

Its a work in progress, I'm not announcing a 'release' at this time, but its definitely usable and I'd love feedback, help with more example patches, help with new features, etc.

It does audio, control and midi: in and out.
No GUI yet, though many hosts provide a default GUI [Ardour, jalv, .. ..]
Tested/developed on Linux, I don't have lv2 running on Mac so I'm not sure if it would work there or not, I haven't heard of people using it on Windows...

Basically the workflow is this: you create a patch that has one or more of:
[inlet~], [outlet~], [send $1-lv2-blah], [receive $1-lv2-blah2], midi input or output objects
And some a couple messages to define the name and unique URI for your plugin.
You then save this patch in a directory in the pdlv2 'plugins' directory and call the patch 'plugin.pd'.
Then you run 'make', this runs a script that parses your patch to figure out how to wrap it as an lv2 plugin, then writes the files it needs to do that and builds the lv2 plugin.

Anyways, if you're interested take a look at the github link above, feel free to email me at my personal email: alex@x37v.info, or contact xnor on freenode/#dataflow

-Alex