TfL have released their annual one-stop-shop for travel advice over the festive period. tfl.gov.uk/festive provides all the information that you might need for travel on roads, rail, underground, DLR, river services and many, many others.
As has now become ritual, a sponsor has been found the transport network over New Year, which will be running as a free service and later than normal (perhaps a taste of things to come). Diageo are backing the scheme for the third year - which runs from 23.45 on 31 Dec until 04.30 on 1 Jan and covers the Tube, trams and DLR (and the last trains leaving London Overground).
The Congestion Charge is to be suspended between 25 December and 1st January (probably not a sign of things to come).
There are a number of engineering works being carried out on the Tube over the period however, and travellers should check on TFL's website for more information before heading out. A full (bus, DLR, Tube) service suspension is running on 25 December.
The website has much more information, and london.gov.uk/nye also has information about travelling about the city on New Year's Eve.
Enjoy the festive break!