Just seen this rumour report at the Photo Rumors, with source from a Russian forum:-
http://photorumors.com/2009/11/30/new-pentax-d-fa-100mm-f2-8-macro-wr-lens/
Well, from the photo, it looks like it is REAL! And, it matches well with the recent "rumour" of the "old" DFA 50 and 100 Macro lenses are just being discontinued.
Besides, the aperture ring seems to have to go forever, as even new DFA lenses possibly will not have that anymore.
In fact, my bet is that Pentax is just preparing for the Full Frame and the DA lens line is being aborted. Whilst they are doing that silently for the Switch Back, it is just impossible to leave no trace and clue for us to know! ;-D Um.., the first leak was back to May and March earlier this year, when there was a leak on the "fake" new lens roadmap as well as when Pentax abandoned the lanuch of previously announced DA* lens and AF TC 1.4X SDM, respectively, which both I reported.
If you believe all the "rumours" that I have reported and my wild guesses I have made here so far, things that are going to happen (if it is really true) look quite logical and they are agreeing with each other. Just say, it is very logical for Pentax to stop production of lenses such as the DA 21 (when there will be a DFA 20) and the DFA 50 and 100 (when there will be the new DFA 100/WR) and etc. And, let see when there will be a Full Frame Pentax body to come!
If you are really interesting in a Pentax Full Frame, my this event log and summary maybe a good read for you:-
http://ricehigh.blogspot.com/2009/10/old-question-will-there-be-pentax-full.html
Indeed, I am one of the die-hard old Pentaxians whom have been urging for a Pentax Full Frame for years. If the day really comes, I will be much happy and I am almost sure that I will buy one. By that time, all my old Pentax excellent film lenses will be given new life, even for those consumer grade ones - most of mine are also very good actually. Unconvinced? Just see my recent measurbation samples posted for the FA 24-90 (which was just the kit lens of the MZ-S) on a cropped APS-C K-m, which shows the lens is just really great optically (although it sucks mechanically, which then gives people of a wrong impression about the quality of this lens - which was the most unwise thing of Pentax for making the lens looks like that, marketing wise). I had also used the FA 24-90 on my Full Frame (K)5D, it also performed greatly (will post sample photo later..)! So, if there is a Pentax Full Frame.. ! :-D Are we Dreaming? :-))