I ditto others' comments about the "exhiliration" and richness of this dialogue -- any lurkers reading through are likely as exhilirated as I am.  Thank you to all!  

Crystal's comment, below, and earlier (along with others' comments, too) -- have touched upon the differences between listserv lurking and class lurking -- whether listserv participation (or lurking) could be considered valid PD.  IMHO (in my humble opinion) listservs are a vital component of my personal PD.   That being said, I still feel a twinge of "this isn't what I'm supposed to be doing" when I read/lurk/reply during my paid hours.   For years, I saved all listserv messages and read them only from my home computer.   

Then I was lucky enough to obtain a full time position, and it became more difficult to find that time.  I was not willing to give up listservs (as so many colleagues I talk to tell me is how they deal with it -- they unsubscribe or delete without reading), and so I began reading them during work.

I've always frequently forwarded/shared particularly pertinent/immediately relevant posts with others, always including the listserv info.

One benefit to a CMS (course management system) approach would be the ability to have documentation on the 'lurkers.'   Moodle has excellent data tracking reports, which can show the date, number and length of time each individual clicks on any link within the Moodle course.   

As an instructor, this information brings many a satisfied "hmmmm" when I discover that a student whom I didn't think was benefiting much from our course interactive (Moodle) website had actually logged in over 1000 times, spent considerable time "lurking" in various areas.   It might still be a challenge to get that student to post a message -- but surely that data speaks to something!    This is an area I am greatly interested in... how/why/need I convert the lurkers into more online action?   These questions (I believe) are equally applicaple to colleagues in PD situations online.  

Crystal wrote:  <<<I think we need to note that the lurker, reader, non-active participant
might be getting exactly what they need professional development-wise.  We might not need to unlock anything but allow them to learn that way and if there is an accountability piece at the end of a course/offering that is something that will allow the instructor to see if the quiet participant has made gains.  At times it is okay to learn without being actively involved, sometimes the active involvement is so that other benefit and if I am a lurker and quietly benefiting and growing, what is wrong with that?>>

and Crystal also wrote:   <<And is it the facilitator's job to motivate me to interact, react, respond, if my needs are being met without me doing that?  Just curious.  >>
Now, there is a question!  
I see there have been several more responses since I began this reply (multiple interruptions here!), so I'll end for now.
Again, THANKS to all for this valuable, for-sure-to-be-reviewed and pondered again opportunity!
Holly

"No matter what our attempts to inform, it is our ability to inspire that will turn the tides."
Holly Dilatush
ESL distance learning, Dialogue Cafe, Volunteer coordinator
Charlottesville City Schools Adult Learning Center
1000 Preston Ave., Suite D
Charlottesville  VA  22903
(434) 245.2815 office
(434) 960.7177 cell/mobile
http://theHsmile.org  ['home' to several Moodle CMS (course management systems/virtual classrooms)]
http://www.Charlottesville-ESL.org 
"Live with intention. Share inside~out smiles, inspire hope, seek awe and nurture in nature."