Nortel just released Release 2 of their Agile Communication Environment, communications integration middleware that can help create communications enabled applications across multivendor communications environments. In my mind ACE represents one of the crown jewels of Nortel technology.
Multivendor Hotdesking is highlighted as a key new capability, which had been developed for HSBC as a lead user.
Of course, single vendor hot desking is a feature of most IP Telephony systems, allowing users to walk up to any IP phone. log-in and take it over.
What's very interesting about the Nortel solution is that it can work across IP telephony and UC vendors and even include desktop video systems (like those from Tandberg), a key differentiator.
Maybe one of these will become reality, sooner rather than later, if Nortel Enterprise is acquired.