New "pushes" coming up.

[DeeBye]

The next push will add some previously unavailable stuff.

# Many objects in the world have undergone data format changes to reduce memory usage. As an example, Stormwind in particular will use half the memory that it currently uses. Framerate Improvements!

# If everything goes as planned, Druids will be available for y’all to try out!

# Several new zones and dungeons are being added!

# New class specific quests are being added!

# And so much more ...

Eventually there will have to be a push that adds the Horde. I don't like the sound of this one, because:

Due to heavy changes in the way we store all our data for the game, the Horde/Alliance push will be nearly the same size as the original download. Unfortunately, this means we won’t be able to patch you this time around, and instead will ask everyone to redownload the client via BitTorrent.

Another 5 day download makes me sad :(

[FoxBat]

Pretty sure that's all referring to the same push, which is the next one, which includes horde and the insane download. The blizz rep clarifies elsewhere on the forum.