If you see ‘teh’ used here on the SDMB then you can assume that sarcasm is implied. If you see it used elsewhere, assume it was written by a child.
Only the stupes. 
Unless you are referrring to some kind of garden implement. Then it’s just a spelling error. Like ‘existant’ for 'existent."
Odd artifact of the technologization of our culture, #38: In cyberspace, the nerdier you are, the cooler you are.
I think I first heard in an old Margret Cho stand-up routine where she was making fun of her ignorant mother who would ask her about her friends “Do they have teh gay??”
If you’re using Firefox 1.5 or better, the SpellBound extension has a development version with inline spellcheck; it underlines in red misspelled words right after you type them. You can get it here. The dictionaries are available here.
I am running 1.5.0.7 yet it won’t let me install spellbound. 
Try saving the .xpi file someplace convenient (like your desktop), and then drag its icon into the Firefox icon, or right-click it and click Open With, then select Firefox.
Firefox 2.0 incorporates the spellchecker. (The Release Candidate is available for download now; I’ve been using it for a week or so and it works fine, although if you’re uncomfortable with beta releases, which may not work with some extensions until they’re updated, then it’s best to wait for the official release.)
Or that it’s an uncaught typo.
I do “teh” and “adn” so often that if auto-correct didn’t exist, I’d have to invent it.
Yes, and please note that I was careful not to use “the” in any of these sentences. Guardere hates me.
I’ve definitely seen a larger use of the word internets after Bush spoke it, and it’s almost always used mockingly. The other words have been around like you say, but they definitely don’t get used as much now.
As for “teh”, it ranges in use and the context is key. “teh Republicans” could simply have been a spelling error or it could have been used in a mocking fashion. For example, if I were to say the Republicans were behind 9/11 your response may be “omg not teh republicans!”. Of course you can be much more effective in carrying that emphasis by deliberately changing other things as well:
“omg naught teh republicans!”
“omg naught teh republicans!!!11”
“oh em gee naught teh republicans!111”
Leet speak isn’t necessarily about being cool. It’s just a language that has developed to carry meanings that are much more difficult in text. Of course it’s often used just to piss people off (like substituting numbers everywhere) but I’m seeing it more and more as a way to convey that what you are saying has more substance than just the words themselves, much like tone is used when talking to someone.
You’re probably right about Bush and “the internets.” Another reason that’s popular could be you can actually pronounce “the internets.”
People can’t say “teh” or “pwned” out loud. Or at least, I don’t think they should.
Ahem. It’s spelled Gaudere.
Band name!
So would a current cover band be called Teh Teh?
Or “Teh The,” as a mocking commentary?
Now, now…
Maybe “shouldn’t,” but I did eventually learn that you can pronounce “pwned.” I’m told it’s spoken “poned.”
Well, my thesis supervisor’s last name was Teh, pronounced more or less “Tay”. He always got really annoyed at students who’d left auto-correct turned on, when they turned in papers addressed to “Dr. The”.
So whenever I run across people talking about “teh internets” or whatever, all I can think of is my former supervisor.
I say “teh” and “pwned” out loud in conversation with a couple of the guys at work (who are also pretty up with computers and internet slang)- and for the record, “teh” is only ever used in the sarcastic, mocking sense- much as it is here on the SDMB, whilst “pwned” is pronounced as “pawned” or “porned”, and is quite separate from “owned”.
“Teh” is pronounced as it’s spelt, as a general rule.
My brother takes it a step further, and even pronounces “lol” and “ROFL” as words (“Loll” and “Roffle”, respectively).
“n00b” is also becoming a legitimate word around these parts, with the same meaning as it has on the internet. I’m also experimenting with “All your (noun) are belong to us”, but with less success…