I keep receiving those anonymous tips (three so far) about a new Nikkor AF-S 50mm f/1.2 lens:
Nikon are working on an autofocus upgrade of the classic 50mm f/1.2. It is still rather far from production however the optical formula is very similar to the Ai-s lens. The auto focus of this lens is different than the currently used in AF-S lenses. The upgraded focusing is what would be consider an evolution and not a revolution. It's slightly faster on existing bodies. It allows quick stop-to-stop autofocus while maintaining a comfortable manual focusing speed- which is particularly important with the shallow depth of field of a lens this fast. Current models are very much engineering samples and specific ergonomic considerations are still being evaluated.
Could this be the PMA surprise? One of the messages I received said that this lens will be released together with the 24mm f/1.4, which means next week (contrary to the above paragraph which states that this lens is "far from production"). Those are conflicting stories, but are pointing to the same product which is not really in anyone's expectations for this year. This is what makes this rumor interesting and worth sharing with you.
Since the source is unknown, I will rate this rumor @ 50% release probability.