I don't think there'd be a problem with multiple users in one hall. I imagine that like with the similar ESU remote controller, or with DECT cordless phones, each handset has to be 'logged in' to it's base station. It's all very... digital.
Roco MultiMAUS Pro - Wireless
Roco have announced a wireless MultiMAUS.
The advance information we have from Roco is in German so the details are a bit sketchy. It looks like a complete starter system comprising the base unit/amplifier, Rocomotion software & the first handset (which looks like the wired Multimaus, except that it's blue) has a RRP of 399.00 euro, with extra handsets for 199.00 euro.
It look very much like a radio system & not IR.
I'll post more details when I get the English version catalogue (probably in a few days).
UPDATE: Info and links to product, a couple of posts down.
