The most significant addition is the ability to skip through the lengthy first phase of evolution by using 'evoadvantage' which allows you to use any existing creature from the Sporepedia.
As well as some graphical enhancements, fine tuning and numerous bug fixes, users can now take advantage of style filters
The official site states:
To get the patch, launch the EA Download Manager to download and install it. If you didn't install the EADM when you installed Spore, you can get it from http://files.ea.com/downloads/eacore/eadm-installer.exe.
This is a PC only patch. Mac users should check back soon!
Source :: Official Spore site