Great guide, I really like Bundler's gem template and tools. You may want to mention the build and install rake tasks which were handy in testing locally before pushing my first release.
⚡ rake -T
rake build # Build magic_smoke-0.0.1.gem into the pkg directory
rake install # Build and install magic_smoke-0.0.1.gem into system gems
rake release # Create tag v0.0.1 and build and push magic_smoke-0.0.1.gem to Rubygems
Add mention of 'rake build' in the gem guide. Fixes #15