With the start of Season 2 of Game of Thrones HBO has updated their Viewer's Guide website with a whole host of new information. Most notable is a new map that shows a lot more of the eastern continent of Essos than previously seen, although not all of it (Asshai is still off the map, though Qarth and the edge of the Jade Sea are shown).
So is this map 'canon' for the books as well? Mostly, certainly as far east as the Red Waste and Lhazar. However, George R.R. Martin recently re-conceptualised the map of Essos past that region. The HBO map is based on older material and should not be considered canon for the books (although the approximate locations of Vaes Dothrak and Qarth should be correct, the coastlines and some of the geographic detail has changed).
Amusingly, since it doesn't show the known coast of Sothoryos, the map fails to resolve the age-old question of whether the Jade Sea is a landlocked semi-inland sea (like the Black Sea) or not. Speculation may continue, at least until The Lands of Ice and Fire map book (which will be canon for the books) is released in October.
Note that at the HBO website the map is zoomable on quite a large scale, and shows locations not visible on this map, such as Vaes Dothrak and Lhazar.