For each of the posts at the blog, you will first see a LOLCat with all the mistakes that the LOLCatz typically make when they use English. For example, here are the Guilty Cats:
There are two little buttons there: Show Correct Cat and Hide Correct Cat. When you first see the image, you see only the uncorrected LOLCat:
There are also some grammar notes at the bottom of each post that explain just what kinds of mistakes the cats have made.
There are about 60 of these cats from the summer and I hope to add some more this year, as part of my eternal quest to show that the rules of English writing really can be fun. Sometimes the cats make totally ridiculous mistakes that are easy to fix, but sometimes they make mistakes that are just like the ones "hoomanz" make too. :-)