No the external drive does not appear in Disk Utility.
Also wondering why iTunes cannot see either my iPhone 4 or iPad 2, both connected via USB on the front of my Mac Pro?
The difficulties I am experiencing are similar to what occured when I first tried to upgrade to ML. Back then, shortly after ML's release, post install ML would switch off my Apple keyboard.
I have waited since then for a fix, and had hoped the issue to have been resolved by 10.8.2. It appears only partially resolved.
In the end the Apple employee at the Genius bar re-installed Lion and mentioned that after a Google search other Apple users with the same model as mine were reporting the same issues.
I may have to return to my AppleStore to have Lion reinstalled post a clean wipe of the ML HDD.