Florida Turnpike, pass up 27 and watch for 429 (Western Way). Take it towards "Tampa". This is a brand new toll road, it will cost you $1 to get to Exit 8, which is the exit for WDW. It's great - I estimate it saved us at least 20 minutes over the 27/192 way.
P.S. It's still not on any maps,so don't be confused.