From the Plan B site [and Matrixsynth]:
Shipping in early June, 2007, the Plan B Model 28 Programmable Tap Clock is the second computer-based product in the Plan B line and addresses the need for an accurate tap input-based timing clock for analog synthesizers. Along with the quarter note base duration, the M28 provides separate eighth note tuplet and eighth note triplet outputs and a single SERIAL OUTPUT which allows the user to construct polyrythmic combinations of the three note values, determined by a voltage level present at the SELECT input. For more information and complete functional description click here
This thing is SO cool. Not only is exactly like something I was looking for (or hoping to achieve with the MIDI-CV clock and Plan B sequencer), but it also fills out the last 12HP that I hadn't decided on for the second case.
I'm so stoked on this unit, I can't wait...even though I won't actually be getting it until the first case is done :(