My local rag carried an advert last week with the banner "Money off"
giving
the new bus and tram fares and the date of 27th February for the peak
Oyster
fares. That's the only place I've seen it apart from on this thread.

This Evening Standard article may be of interest:

http://www.thisislondon.co.uk/news/l...ing%20Standard

Yes, I'd heard about that and was just about to read it.

I should add that as well as the 1/3rd page "money off" advert, the local
rag had a similar sized one on the page before saying "40p off" and
projecting the 80p Oyster fares as a special offer :-)