Amongst the many common emotions felt by readers whilst reading A Game of Thrones for the first time is confusion when the action switches to the Free City of Pentos and they thumb back to the map only to find it's not on there. The confusion is increased by all the people referring to the body of water between the two continents as 'the Narrow Sea', which makes it sound like the other continent (unnamed in the books so far but dubbed 'Essos' for the TV show, a name approved by the author) should certainly be visible on the maps in the books. Given that Daenerys's story ranges over many regions of the vast eastern landmass, it does feel slightly odd that her part of the story (save Slaver's Bay in A Storm of Swords) goes resolutely unmapped in the books, though it does help reflect the 'off-the-edge-of-the-known-world' feel of her adventures.
Fifteen years after people first started scratching their heads over this (not to mention multiple fan maps of the area, based on information in the text), we finally get to see George R.R. Martin's map...but not for the first time in A Dance with Dragons as many had assumed. Whilst ADWD will indeed feature a map of the Free Cities, we will get to see the first canon map of the area on the HBO show. The opening title sequence of the series ranges over a map of Westeros and the Free Cities, with each location featured in that episode 'popping up' out of the landscape. So in the first episode we will see Pentos, whilst later episodes will feature the Dothraki Sea, Vaes Dothrak and presumably Lhazar.
Furthermore, if the 15-minute preview of the first episode features the title sequence, that means we'll see it tomorrow evening (EST) on HBO (and for the rest of the world, shortly thereafter on the HBO website). A minor but nevertheless interesting bonus for the book fans from the TV show.