Global Categories and Tags for marketpress, classifieds and listings

Hi,

As this is a WPMU site community, multiple websites running off one wordpress install:

Is it possible to have marketpress, classifieds and listings running off a global cat/tag system powered by post-indexer?

It has been requested before, but not for all 3. Surely, by implementing a standard indexer based global cat/tag system, it would save website owners time, and wpmudev work down the track...

Any +1s

Cheers,

Johnny