I'd say it's correct. This part of the sentence is, AFAIK, commonly called an "introductory clause" and is usually followed by a comma.

Seems fine to me as well.
Maybe with a "that" if no comma?

See that's the thing. I wouldn't put a comma there if there was a "that," and just because that word's omitted, I don't think that necessarily calls for a comma. Meh, maybe it's just me.

To me the comma is essential, if only because there's a full breath pause, a complete break in the rhythm. The sentence without 'that' is already colloquial, more spoken than written English. It's clearly reported speech, so it should preserve the speech rhythm.

Besides, if you omitted the comma, the sentence would be liable to be misread: The fact of the matter is McKeesport (which makes no sense).

I wonder if you were thinking about the rule that no comma should intrude between the subject and the verb (in modern English), unless there's another reason for it such as a clause or appositive phrase. But here the break comes after the verb, not after the subject.

Replace the comma with a colon and it is grammatically correct:

"The fact of the matter is: McKeesport has the kind of speed that you can't simulate."

For an excellent and entertaining book on English grammar allow me to recommend "Eats, Shoots & Leaves" by Lynne Truss (ISBN 1-86197-612-7)

If needs the comma unless you add "that", in which case the comma is omitted. Neither a hyphen nor a colon work in my opinion because it's just to indicate a brief pause - what follows is not a clarification or elaboration or even an aside.

I guess the whole "if a 'that' were in there" thing is what's confusing me. I always thought since you wouldn't put there w/ the 'that' that you wouldn't there if it were missing, too.

@Bill: What about, "The fact of the matter is this:..."? Does the colon work there? (Kind of like German's, "Die Lage ist die:" or something of that sort.)

I would also have placed the comma (and not a colon) in the same place.

The colon looks wrong to me too. (German, in fact.)

It's okay, though, in Charlie's revised sentence in #7.

I haven't read Lynne Truss's book; however, several reviews said it was entertaining and generally good, but not itself error-free.

Charlie, yes, the colon works in your example because what follows is a complete sentence.

The fact of the matter is this: X gave Y a bloody nose and that's all that matters.

The fact of the matter is that X gave Y a blood nose and that's all that matters.

@Charlie(US) I too find the comma most strange. The main verb is the verb 'to be'. The sentence should therefore be reversible. 'McKeesport has the kind of speed that you can't simulate is the fact of the matter.' and reversed, it clearly needs to begin with 'That'.Without the reversal,the 'that' is optional,but no comma or colon is required.
The two subjects of the verb 'is' are 'The fact of the matter' and 'McKeesport has the kind of speed you can't simulate'.When the verb 'to be' is used, it is not usual to separate its two subjects with a comma - The brown haired boy is(,)the blond haired girl's brother.

I also don't like the comma; I guess the colon would be OK, although it does look a bit ... extreme, maybe?

Maybe the confusion comes from sentences like this:

The thing is, he's really fast.

A comma is OK here, as "the thing is" is more of an interjection or introductory clause, or whatever it's called, similar to "in fact" or "actually". It isn't the subject of the sentence, which becomes apparent when you say "The thing is ..." and someone else snaps "Yes, what is the thing?!"

" the thing is (informal) used to introduce an important fact, reason or explanation: I’m sorry my assignment isn’t finished. The thing is, I’ve had a lot of other work this week. " http://www.oup.com/oald-bin/web_getald7index1a.pl

"The fact of the matter is" sounds a bit similar, but in fact I think it isn't, it's the subject, as Jgmci says.