As more and more companies start adding MIDI 1/8" Jack inputs to their modules or standalone devices we have started to lose the MIDI thru... There is also the problem of two different standards with MIDI on 1/8" jack... Step up Delptronics, with their MIDI Thru module, this solves both of these problems.
More info at Delptronics
Deep look at the new generation interface
Artist, Producer, Remixer and Performer
Desktop polyphonic MIDI and CV/Gate