As of this morning, you can use your contactless debit or credit card to travel on the tube, DLR, Overground, tram and some national rail services as well as buses, which have been accepting contactless payment for some time.
It's an alternative to your Oyster card — and one which Transport for London might well prefer us to use, as it doesn't cost them as much to administer. We've previously looked at how the system will work, and also asked the opinions of people involved in the pre-roll-out trial, and the basic low-down is this: your card doesn't get debited as you travel, but all in one go overnight, so if you want to see how much you're spending you either need to register for an online account and keep checking it or keep a running tally in your head. And, needless to say, watch out for card clash between your contactless card(s) and your Oyster — that's when the system registers more than one card at a time, or a card you didn't want to pay with.
If you use Pay As You Go a lot, contactless might be a better option, as the system will cap your Monday-Sunday usage at the same rate as a weekly travelcard. That's something that won't be available on Oyster for some time.
Let us know if you used your contactless card today and how it went. Or watch this rather twee video from TfL to find out more.