This thread is old, but since I'm pretty new here I thought I could answer the question for other people if they want to know: yes I have sent stuff to Valve in the past. Namely my custom campaign for L4D2 which got featured around Haloween last year.
Now I got to say, L4D2 campaigns usually get more attention because they take up more work and time than a TF2 map so Valve noticed it without me contacting them, but usually if you want to ask a question to Valve, your best bet is to contact Chet Faliszek.
Chet is a very friendly person but keep in mind that he gets tons of mail every day. Sometimes he'll answer a mail the next day if you're lucky, sometimes after a week, sometimes not at all.
And judging from what is being said in the L4D2 Mappers Mailing List in which Chet is active, yes they seem to still take community made maps through that link you gave for TF2.
However, other than the recognition and the satisfaction that Valve themselves seem to like your work, you won't get any rewards. Well at least us L4D2 mappers didn't get any.
Just give it a shot. It doesn't cost you anything.
PS: "Did anyone sent anything to Valve?"... tss tss tss it should be "Did anyone send
anything to Valve?"
Sorry... it's stronger than me.