Zueri Rollt does still exist in Zurich; I walked past their big trailer at Bahnhof Enge the other day. According ot the following page (in German),
http://www.stadt-zuerich.ch/content/...standorte.html
there are also two stations at Hauptbahnhof, one at Buerkliplatz and one at 'Globus City' (???), and of course there's the one at Enge.
Conditions given on site are what other people have stated:
- free
- ID required (just to show)
- 20 CHF deposit
- can return to any (Zueri Rollt) station
- 10 CHF to keep the bike overnight, othewise return by 21h30