Obviously there have been rumors going around about there being higher maps when 1.0.0 came out. But how do you get these taller maps seeing as how most of us still have the 128 tall maps being generated?

It's simple as to why most of us still have the 128 tall maps. You've gotta install a mod for this!

Where can you find this mod?
http://www.minecraftforum.net/topic/664311-100-dynamicheight-v211-256-512-1024-2048-high-worlds/

How do I install it so that then it works?
First you've got to have modloader installed first in your .jar folder. Then you will be able to add the height mod into the .jar folder as well.

(for a more detailed installation instructions page for installing the mod loader go here:
http://www.modloader.com/modloader-of-minecrafty-1-0-0/
you can also get more mods from ^^ this ^^ same website, on the home page of the website that is.)

Hope this helped for those of you who were wondering about the whole taller maps rumor!

Warning
Don't attempt the 2048 height adjustment! 2048H = severe lag (even for some of the best computers, which will have slightly less lag severity but still have lag)! 1024H is more than likely a similar situation