Leica 135 f2.8 Elmarit. I saw this lens a few weeks ago at Kurland Photo's 5th floor store on Broadway (next door to the Leica Gallery.) I did not want this lens for all the reasons that very few people lust for it; namely, it's big, it's hard to focus, and it defies the whole ethos of Leica-ness. But the lens was competitively priced (read, cheap,) is pristine, its sn 3486xxx puts it at the tail end of the run, and it seems to have decent sharpness with what I'd call a dense rendering with my M9.
I'm only into RF since the early issue of the M8, so coming from the beefy pro-Canon realm, the lens's ergonomics feel comfortable. I haven't used it much, but I can see its niche for my purposes being people shots with flash at various events (mix of candid and portrait)--family and work related, much the same as when I used Canon tele-zooms. Better because it is in every way a Leica lens.
By the way, Kurland will be operating the new Leica store in SOHO when it opens (they hope) in a month or so. I had a nice conversation with staff about the cultural shift of the new store from a place that now does most of its business by phone or on the web. Very little foot traffic--I've been there 4-5 times, bought a lens previously, and have always been the only person in the store (itself arranged more like a gallery than a retail "operation.") SOHO will have tons of foot traffic, and serve people with just a surface knowledge of the high-end product, if that.
Interesting conversation about Leica's business plan, leading to serious inroads into mainstream high end SLRs. I was impressed by his noting that their particular business is not about offering bargains or gear which is pretty much standardized, but about giving reliable information--service--about the product. They do that well. There's a clear commitment to retain that, but also a concern. I wish them luck.