With ubuntu's new branding, GRUB needs a face-lifting too, and here it is.
To use this, you'll need burg, an updated version of grub 2.
There are two versions, one with text and one without text.
Here is how to instal BURG:
Add ppa:bean123ch/burg to software sources
sudo apt-get install burg burg-themes
Also check out the wiki for some in depth information: [link]
To use this theme:
Extract the tarball to /boot/burg/themes
While booting in the grub sereen, press 't'
In the theme selection menu, select radiance or Radiance Text.
Here is link to Radiance Text:[link]
This theme is based on code from sora theme, so all credit goes to the original authors.