Disregarding midgets, according to my spreadsheet of 1493 (and ever-growing) porn stars, there are three 4' 10" ladies (Gen Padova is 4'11"):

Bisexual Britni (88 lbs, 34B-21-32, movies 2001-03)
Danielle Dynamite (aka Dyn-o-mite) (110 lbs, 34B-25-34, movies 1999-2004)
Tami Monroe (90 lbs, 32D-21-30, movies 1989-2001)

Given her sluttiness (getting peed on/analed by Max Hardcore), I think Bisexual Britni takes the lead in this disscussion.