When it comes to these forums, if I come across really poor grammar and spelling I generally assume that English isn't the poster's first language. I tend to forgive that kind of stuff. And especially since these are tech forums, I expect the nerd-speak (rofls and r0x0rz and whatever).
Looking on other forums - in particular ones with a younger user base - the rampant shorthand stuff irks me a bit, but I credit it to just being a product of the instant information generation - in which case shorthand is actually more useful to get a message across as fast as possible with the least effort. I generally assume they will grow out of it the older they get. If not, so be it, language evolves. It's not like we're losing words entirely in Orwellian fashion.
When I start seeing it creep into emails at work - using acronyms for things and smileys and improper spelling and whatnot - I just generally lose a little bit of respect for the person every time it happens. I imagine others do the same. On the flip side, if you can do your job well while having poor writing skills - then it really shouldn't matter.
And English is definitely not a dying language.