Noticed this the other day - good news for those using the station into Central London although it doesn't seem to change the travelcard cost at all. Seems this was part of the Northern Line extension agreement.
Cost of commuting from Kennington reduced as station rezoned
The change sees it go from being a Zone 2 station to Zone 1/2, meaning a single fare to central London will be reduced to £2.40
www.standard.co.uk
Commuters travelling to zone one stations by tube from Kennington will see their fare reduced from Sunday after the station gets re-zoned.
The change sees it go from being a Zone 2 station to Zone 1/2, meaning a single pay-as-you-go fare will be reduced to £2.40 at any time of day.
The move comes as part of Transport for London’s preparations to open its extension to the Northern Line later this year.