It's exciting to know these things early and be involved in the process. I saw Andrew's post over the weekend and immediately had checked for one of my plugins. Turns out there is a little bug with the tooltips that are added, so I could immediately open a ticket on Trac. Basically no excuse for plugin developers who wait until after April 15 (release date of WP 3.9) to see whether or not their plugin still does what it says on the label...