Yes, you're right jschuur. Ginger software only gives windows installer, and they don't have an api documented. Since I am Linux user I can use their web based tool only, http://www.gingersoftware.com/features/grammar_checker.html. I had an idea to wrap it into a rubygem and then gingerice was born.
I have no affiliation with them. I just see their service is awesome. I am not sure about their rate limits and usage term. That's why on Readme page I state "hope they will keep it free".
I have no idea about integration yet. I use command line for the result and ruby session for more details result. I think realtime feedback for comment (like derwiki's comment) is nice idea.
You're welcome wesray, I hope the same thing too. I use the key from their website and I don't see their rate limits yet. The test is definitely required to ensure everything working smoothly.