Besides two new maps, Badlands and Goldrush, Valve will also ship a really large-scale-modification for Team Fortress 2 in the next weeks. This is what the blog of PC Gamer UK just released an article about.

This large-scale-modification will not only bring the two new maps and with this also a new game mode, although this in itself would actually be rather exciting enough already. As Tom Francis from PC Gamer writes:

Furthermore with the modification new items and upgradable weapons will be released; most of them can be unlocked via successfully gaining some of the games' achievements. Those new items and weapons are not just uninspired upgrades; they really seem to be able to bring a whole lot of new tactics for every single class of the game. One of the revealed unlocks will be for the Medic and is called the "Overhealer". This permanently will double the standard health but won't be very good in building up Ubercharge anymore, which is the downside of it. Valve even seems to consider of not letting Ubercharge work with the new item at all. They are obviously still moving things around, because with poor balancing the game could easily be at stake. But Valve promises that they won't let this happen.

Not only is the new content large-scale, it also seems to be large-scale promising.
You should probably prepare for learning some new skills around February or March this year.