A recent Article published on Techrepublic lists 10 Grammar mistakes that are extremely common in all online communication, including forums like this one.
An interesting thing showed in the discussion there on the article, the majority of people who participated in the discussion absolutely detest the "l33t" speak used in posts, emails and im's. Why would this be important? These People Hire Programmers!!!! That's right, most of these people are IT Department heads, and potentially are your bosses as programmers.
Do you think that it's a good idea to use im shorthand everywhere you post any message?
Then read the article and ensuing discussion. "l33t" speak in posts tells people you are either to stupid to use correct grammar and spelling or to lazy to do ANY job right.