The 1899.co.uk site certainly shows an increase to 3p/minute and some are reporting having been charged that today.
From my BT landline, I've just this minute tried dialing my own mobile using the 1899 prefix and got a "3p per minute" tariff message.
OTOH, posters on the MSE forums report that, using the 0808 freephone number (i.e. the access route those with non-BT landlines have to use), it's still 2p/minute.