This is a breaking story and there isn't much information.
Adam Schefter is saying Winslow has been traded to the Buccaneers for draft picks. Early speculation is a 2 and 5 or 3 and 6. Obviously, this post will be updated as news breaks. If any of you have updates, please provide them in the comments.
UPDATED: Quote from NFL.com story from George Kokinis:
"The Cleveland Browns thank Kellen for his contributions to this organization over the past five years," Browns general manager George Kokinis said in a statement. "We appreciate his passion for the game and wish him success in Tampa Bay. The draft picks we have obtained through this deal will give us greater flexibility as we look to infuse more talent and create competition and depth on this football team."