I've never heard of this before.
What's your OS ?
Do you have the latest version installed ?
If it fails to appear in the Extensions menu / toolbars can you please check if the file SketchUcation.rb and its subfolder are still in your Plugins folder...
If it is there try this...
Open the Ruby Console [under Extensions > Developers Tools] and type or copy/paste this in + return
What happens ?
Do you have similar issues with any other extensions ?