Update: Added missing brackets and an afterthought at the bottom. And corrected the error blakem pointed out below.

You don't need a regex, a simple index will do fine. This has the additional benefit that $run will give you a comparative value for determining the value of the hand.

if (($run = index('abcdefghijklm', $sorted_values,0)) > -1)
{
 # Do stuff...
}
[download]

In fact, if you arranged for your sort of the cards to sort aces above kings, then you could use the $run values to determine which run has the higher scoring value. (I think. I'm not much of a card player :^)