As mentioned on wp-hackers. Please note that I just went over this with a fine tooth comb, but it still needs a little testing and double checking just to be sure. ;)
Demo: http://test.viper007bond.com/wordpress-latest/wp-login.php
What's new (oh where to begin?!):
* wp-register.php moved to wp-login.php?action=register and redirect added in wp-register.php
* Registration page is currently only like half styled in the SVN. This has been fixed.
* Multiple errors can now be displayed for each form
* Bottom links made to look pretty (they looked bad if registration was enabled)
* Fixed some display issues in IE
* Made the WP logo much easier to click in FF (it was all funky before)
* Removal of all references to wp_die(). All errors and messages (nearly) are now reported via the standard error area.
And the most important:
* Tons of new hooks and filters
You can now restyle the login pages however you want due to the addition of a hook into the <head>.
Each form also now has a hook in it so that you add new input fields (say their sex or birthday or even a CAPTCHA). There's also of course a new hook for each that allows you to handle the $_POST and then set an error if your field is left blank, not filled in correctly, etc. This error will be displayed like any other error.
For example, check out this example which was created via a very simple plugin:
http://img215.imageshack.us/img215/5851/wpregistercolorjt7.png
