I just pushed a fix for this that'll be included in 3.0.2. In the mean time, you can grab the updated index.php file from https://github.com/silverstripe/silverstripe-installer/blob/3.0/index.php

Thanks Simon. Will give it a try. Cheers

I haven't tried the Simon's patch yet, hands are full today.
You have to make sure that the installation script finishes cleanly (normally redirecting you to your new installation).
If it ends warning that it cannot use clean urls then you need to make sure that the directives on your Apache is configured with the mod rewrite module enabled and that the <Directory> directive in the appropriate web server configuration file (httpd.conf -or vhosts.conf if you are using that) allow overrides. Here's my setup:
<Directory "/Library/WebServer/Documents/silverstripe">
Options Indexes FollowSymLinks MultiViews
AllowOverride All
Order allow,deny
Allow from all
</Directory>
(note that this is a dev setup and bit permissive. It might not be safe for production, depending on your needs)
Hope it helps.