It's been rumored for years and years, but as of now, it isn't happening.
From
http://www.empireonline.com/news/story.asp?NID=24625 and the current issue of Empire:
29 April 2009
Exclusive: The Goonies Talk Sequel
Never say never. Or die.
You may not have realised, but March 17, 2009, was an historic day. It was on that day in Hollywood, California, that all of The Goonies, including director Richard Donner and producer Steven Spielberg, were reunited for the first time in over 20 years* to have their photo taken for Empire's 20th birthday issue.
Naturally, whenever one or more Goonies are gathered together, they're always asked about a sequel, and this time was no different. Here's a little taste of what they had to say.
Richard Donner: "We tried for a long time. Steven and I had many meetings with writers but nothing stuck. It seemed disrespectful."
Corey Feldman: "So I guess the answer about the sequel is that there's always hope."
Donner: "No. No hope."
Sean Astin: "A year from now, ten years from now, 50 years from now, I'm absolutely convinced there'll be one. We'll figure it out. A sequel could be great. It could be s**tty. You never know. But the original is the thing it is and no-one can ever change it."