They evaluated the use of the "thumbs" system that enables each player to disallow a certain amount of maps from the pool for every game he plays.
The least played maps were removed and replaced with some new maps.
A special change was made in the case of the standard map in classic, Lost Temple.
While the classic version of the map had been very much accepted and used, especially pro-gamers lately complained a lot about the TFT "ice" version of "Lost Temple", and so Blizzard decided to re-integrate the original version of the map into the map-pool.
Here are the complete changes from the Post in the Battle.net forums.
Solo
Remove (4)DesertStrife.w3x
Remove (4)Islands.w3x
Remove (4)LostTemple.w3x
Add (2)GlacialThaw.w3x
Add (2)TirisfalGlades.w3x
Add (4)LostTemple.w3m
Random Team 2v2
Remove (6)JungleFever.w3x
Remove (8)Friends.w3x
Add (4)TwistedMeadows.w3x
Add (4)Roundabout.w3x
Arranged Team 2v2
Remove (4)DesertStrife.w3x
Remove (8)Friends.w3x
Remove (4)DevilsCauldron.w3x
Add (4)TwistedMeadows.w3x
Add (4)ColdHeart.w3x
Add (4)Roundabout.w3x
3v3 (Random and Arranged)
Remove (6)Wellspring.w3x
Remove (8)Rockquarry.w3x
Add (8)Crucible.w3x
Add (6)UpperKingdom.w3x
4v4 (Random and Arranged)
Remove (8)RockQuarry.w3x
Remove (8)Sanctuary.w3x
Add (10)RagingStream.w3x
Add (8)Deathknell.w3x
FFA
Remove (4)LostTemple.w3x
Remove (6)Wellspring.w3x
Add (6)Monsoon.w3x
Add (4)Islands.w3x
While I don't even know all of the newly introduced map, I can definitely agree with the ones removed from 1v1 and both 2v2 AT and RT (I don't play 3v3, 4v4 or FFA).
Except for "Devils Cauldron" and "Lost Temple" (which was only replaced by the old LT), all maps removed there are exactly the ones I had "thumbed-down" for my own games!
And I had also missed "Twisted Meadows" in 2v2.
So, great job, Blizzard, imho.
Links: Blizzard | B.net Post | TFT Ladder Maps (old)