It'll give you a giant archive. Extract it somewhere, and then if you want to install it quickly without double-clicking on a bajillion .deb packages, then you can use Terminal to save yourself some trouble.
01.) Press [Alt+F2] and type gksu gnome-terminal - this will request your password since it's opening the Terminal under a root account.
02.) Go to the DEBS directory whereever it may be (you can see what's in the folder you're in by typing "ls" and navigate to a folder by typing "cd NAME-OF-FOLDER" to change directory to there.
EX: For instance, I put my DEBS directory under /home/silare/Downloads/DEBS - I could type cd /home/silare/Downloads/DEBS
03.) Now, assuming you're in root... Type the following command:
dpkg -i *
It should install every package in your DEBS directory. However, there is a folder called desktop-integration as well. If you want to put OpenOffice.org 3 launchers in your menu like OpenOffice.org 2 did, as well as wipe away all of OpenOffice.org 2 (and don't mind wiping desktop-core away with it too) at the same time, then you can also type the following commands:
cd desktop-integration dpkg -i *
This puts you in the desktop-integration folder and then lets you install that last package.
Hope this saves some time for you.