Casual misspellings and grammar mistakes are a fact of life, and nothing to get in a huff about. It's the mistakes that seem to become
common parlance that make me shake my head.
As for txtspeak, 1337, netspeak, etc., I feel like they're fine in small doses, especially if applied in an ironic sense. More so if part of an otherwise intelligible post. When that's all the user seems to be able to write in though, it becomes a problem.