"No Rakefile found" when I run "rake gems:refresh_specs"

When I run my app I get this error:

config.gem: Unpacked gem rakismet-0.3.6 in vendor/gems has no specification file. 
Run 'rake gems:refresh_specs' to fix this. 

And when I run:

rake gems:refresh_specs

I get:

No Rakefile found

I've tried the rake command from various directories within the application hierarchy with no success.

When you generate a rails application you get a Rakefile created in the base directory of that application. This is the directory you should be calling rake gem:refresh_specs from.