Some attendees are staying at Jurys Inn.
Other possibilities are:
Rutland Hotel, Cutlers Hotel, Leopold Hotel, Ibis Hotel, Premier Inn (St. Mary's Gate), Premier Inn (Angel Street).
See Lumenet 2012 locations on Google Maps.
Travel suggestions for overseas visitors:
(1) Fly to Manchester airport from where there are regular direct trains to Sheffield (this takes approximately one hour).
(2) Take the Eurostar train to London St Pancras, from where there are regular trains to Sheffield (approximately two hours).
The blue tram route travels between Sheffield Train Station and the University.
Maps and travel advice