On the radio today, I heard something like, "Kids should bring two pair of shoes."
I've always heard "pair" used as the plural -- interchangeable with "pairs." So I figured it was okay. (Personally, I hate it. But that's just my prejudice and one I wouldn't try to foist on anyone else.)
Today I finally looked it up.
Webster's New World College Dictionary permits either "pairs" or "pair" as the plural, but prefers "pairs." American Heritage Dictionary, remarkably, lists "pair" as its first preference, but also allows both.
As for other usage questions, including whether to choose "the pair is" over "the pair are," American Heritage adds:
The noun pair can be followed by a singular or plural verb. The
singular is always used when pair denotes the set taken as a single
entity: This pair of shoes is on sale. A plural verb is used when the
members are considered as individuals: The pair are working more
harmoniously now. After a number other than one, pair itself can
be either singular or plural, but the plural is now more common: She bought six
pairs (or pair) of stockings.