Whitey - 5:35 am on Apr 16, 2012 (gmt 0)
It's an interesting question, and I don't personally know. Having said that I'm seeing folks busily distributing plugins with backlinks supplied.
Perhaps a better tactic would be to continue distribution of it, but use the enablement as a "tool" to liftthe phone and speak to the website owners about adding some complementary content that you or they could write, with more "natural" links contained within it.
If you're worried about content in say Wordpress blogs losing it's PR, you could even provide the opportunity for you partners to link internally to those blogs and/or apply something into the code for you to adjust those "relevant" links in the code remotely.
I wouldn't stop the success you've had, just ramp up the natural part of it. It would be good to hear from others in this space to see what they have done.