Well, not an official release. But TheJoe is looking for voice-actor volunteers to add voice audio to Monkey Island 2 using a tool called 'ScummSpeaks'.
You can read more in the threads here at LucasForums or here at ScummVM's Forums. The latter one has input from the author of ScummSpeaks, jestar_jokin and you can see his short 'proof of concept' demonstration here;
There's an earlier speech-hack demo by jestar_jokin here.
Source: LucasForums
This is only the proof of concept for working with vars. http://www.youtube.com/watch?v=fNO7HpeWgtU This one, also by jestar, sees edited dialogue with speech. This was done with manual hex editing and he made ScummSpeaks to make it easier.
However aesthetically it kind of sucks.... Voice acting only works when it's really welldone, otherwise it will only annoy people.
Maybe using non-actors in their tests was what made them decide that, unlike in Sierra's KQ5, they'd actually let you turn the voices *off*...