This was even covered by The LOL Street Journal, who wrote
What makes lolcats appealing is that it's simultaneously obscure and accessible. It's an inside joke told in an online lingua franca, but with a bit of effort anyone can become an insider.
"An in-joke used to be constrained by geography and who you knew socially," says Anil Dash, occasional lolcat critic and vice president of Six Apart, which creates several popular blog-software programs. "This is a very large in-joke" that blurs the old distinction "between Net geeks and the normals," he says.
The article is pretty interesting, even for someone who's annoyed at txt speak.
It turns out you can get cat speak wrong, which implies that you can get it right.