Disney yesterday posted the following on the WDW Marathon page:
"Due to unprecedented demand and increased Half Marathon course capacity in 2010, Goofy's Race and a Half Challenge has reopened for registration! Celebrate the 5th anniversary of Goofy's Race and a Half Challenge with 7500 of your closest friends!"There's no word on how many slots are available, so if you're interested in running in the Goofy, you'll want to sign up right away.
In other WDW marathon-related news, the annual half-marathon is 80% full.