There, their, they're,  do we really need to lose sleep over bad spelling? According to this article that appeared in Wired earlier this year, absolutely not:

So who shud tell us how to spel? Ourselves. Language is not static—or constantly degenerating, as many claim. It is ever evolving, and spelling evolves, too, as we create new words, styles, and guidelines (rules governing use of the semicolon date to the 18th century, meaning they’re a more recent innovation than the steam engine). The most widely used American word in the world, OK, was invented during the age of the telegraph because it was concise. No one considers it, or abbreviations like ASAP and IOU, a sign of corruption. More recent textisms signal a similarly creative, bottom-up play with language: “won” becomes “1,” “later” becomes “l8r.” After all, new technology creates new inertia for change: The apostrophe requires an additional step on an iPhone, so we send text messages using “your” (or “UR”) instead of “you’re.” And it doesn’t matter—the messagee will still understand our message.

Standardized spelling enables readers to understand writing, to aid communication and ensure clarity. Period. There is no additional reason, other than snobbery, for spelling rules. Computers, smartphones, and tablets are speeding the adoption of more casual forms of communication—texting is closer to speech than letter writing. But the distinction between the oral and the written is only going to become more blurry, and the future isn’t autocorrect, it’s Siri. We need a new set of tools that recognize more variations instead of rigidly enforcing outdated dogma. Let’s make our own rules. It’s not like the English language has many good ones anyway.

This dude begs to differ:

If you think an apostrophe was one of the 12 disciples of Jesus, you will never work for me. If you think a semicolon is a regular colon with an identity crisis, I will not hire you. If you scatter commas into a sentence with all the discrimination of a shotgun, you might make it to the foyer before we politely escort you from the building.

Some might call my approach to grammar extreme, but I prefer Lynne Truss's more cuddly phraseology: I am a grammar "stickler." And, like Truss — author of Eats, Shoots & Leaves — I have a "zero tolerance approach" to grammar mistakes that make people look stupid…

But grammar is relevant for all companies. Yes, language is constantly changing, but that doesn't make grammar unimportant. Good grammar is credibility, especially on the internet. In blog posts, on Facebook statuses, in e-mails, and on company websites, your words are all you have. They are a projection of you in your physical absence. And, for better or worse, people judge you if you can't tell the difference between their, there, and they're.

Good points, but for how long? For those of us who entered the working world pre-fax machine we can remember how many edits a simple letter went through before it was ever printed and dispersed. People were hired specifically to write all manner of correspondence on behalf of the rest of the company so that the egregious spelling and grammatical construction of the average worker would never see the desk of a customer or prospect.   Then email happened and after a short period of hand wringing over the advisability of poor grammarians being allowed to communicate in writing, with anyone, the floodgates opened and all manner of crappy language started flying back and forth. 'Lo and behold we all discovered we'd rather hear sooner and directly from the source, even if they think there is their, rather than wait for an expertly written reply from an intermediary. Then instant messaging happened and we realized we weren't even particular about vowels as long as we could discern the meaning of what was being written.

Of course this is all situational. If you're selling me copywriting services then you damn well better know when to use "whom," but if you're installing my high end surround sound I really couldn't give a tinker's damn if you're illiterate as long as my ear drums are blown out when I watch Glee. Or whatever.