I just spent all day downloading and organising all of the current zone maps for my own personal use (and map obsession) and have uploaded them to my sendspace lite account in case anyone else wanted them. You can download the .zip archive here (276 Files, 17 Folders, 78.1MB). The file will be automatically deleted by the server after 30 days of inactivity. If that happens, leave a comment and I will re-upload it.
This pack does not include the 4.2 raid maps which have not gone live yet, but everything else should be there. For the gnome starting zone, I believe that you can use the Gnomeregan instance maps. They looked to be the same on both Wowwiki and Wowpedia.
My folder and file structure is somewhat complex so I will attempt to explain it a bit. Folders for the continents and 5-man dungeons are numbered by game/expansion: 01 - World of Warcraft, 02 - The Burning Crusade, etc.... Battleground maps are numbered by the level you can start competing. All other maps are numbered by recommended level. Some of the multi-level instance maps were difficult to name properly because I have either never been in them or do not remember the layout, but I did my best. Leave a comment if you see anything that does not look right.