I'm not even entirely sure how you're supposed to pronounce 'pwned'...

pwoned, powned, pwin'd, p'woned...?

that's just a joke misspelling when it goes down on keyboard/paper. you still pronounce it "Owned"

Neg, while it is a joke mispelling, it has been frequently pronounced "Puh-owned"(light uh, like the h sound in hearty) by a few of my friends(who immediately afterward get hit for being such a geek.) I still think most leet speak is retarded, especially when it's actually spoken, but I beleive you do pronounce the mispellings, at least as much as possible.(harder when they're numbers)

I had a weird problem (as in, it was weird I had such a problem with it) with the real cursing, and that was one of the things that through me off as I was flipping through the fourth edition rulebook the first time. Like many things, however, I got over it. The real f-bomb does have more impact than "Frag you!"

As far as the old lingo, I think my favorite is "Frag me running."

I agree that other things work their way in and fit. Firefly gives me humped and we're humped, which is appropriate far more often then I'd have thought. I also will pull some older lingo like savvy and swarthy, which sometimes have the right feel for a situation. Just about any vocab can find its way into the 6th world. If someone questions you can just make up a name of a trideo that popularized the word.

I vote for the reinstitution of the word "jake" as an adjective, as it was used in the 1920s.
SR already uses "doss", doesn't it? That's pretty clearly an adaptation of the usage the word saw around the same time period.

And I've heard pwned pronounced Pawned, powned and Pee-owned.

I have a friend named Jake. So "Less than Jake" is a common phrase.

...I tend to infuse a fair amount of Britspeak and Brit Slang (London Sourcebook) since I am currently running my campaign in Europe.

...basically, the way the English speak as opposed to Americans (don't remember where I actually heard the term), more appropriately referred to as "Queens" or "King's English" . There is a short "translation" table in the beginning of the London Sourcebook. In an appendix there is a lexicon of 2050's British slang.

apartment is a flat, guy is a bloke, that sort of thing?

I've not got the London Sourcebook. Do we still say 'init', 'diamond' and 'geezer'?

Incidentally, most people don't speak the Queen's English. I think the most common dialect is known as Estuary english, but then I'm no linguist.

I have a very funny mental image of a group of runners from Tyneside, Birmingham, Dorset and the East End of London...

...they don't have a full lexicon. The table is of the more common terms a tourist to the UK would come across.

My group almost exclusively uses real world (USA: PA/MD/VA local) vocabulary for anything that isn't viewed specifically as game terminology (i.e. archtypes like Street Samurai, Technomancer, etc.)

When it comes to the F-bomb, we generally use Fuck. Frag isn't completely interchangeable (imho), and we use Frag in game when specifically talking about killing someone. I've been known to use Frack (from Battlestar Galactica) in groups of mixed-age players or when playing in a home where children are present.

One exception is the word "slitch" which a couple of us have adopted both in and out of game. A great combination of terms for situations where either one simply isn't descriptive enough.

How bist, Rosie my love? Ee be a-going running anywhen?

Ooh ar. Thaat Mr.Heath be proper comical though. I be coming right close to a benny whan he be blethering on abowt Devonshire folk being zat.

Tha Wazzock

... too bad you aren't on this side of the pond. Be right fun t' ave ye in me campaign.

Now I need an excuse to send my players to Europe so I can use Planescape planar cant.

If your PCs won't go to Europe, then just send Europe to them...