This isn't linked yet on the Cubs website, but here is the info from an upcoming press release:
The Chicago Cubs today announced television play-by-play broadcaster Len Kasper has received a contract extension through the 2011 season.
"I am thrilled to extend what has been, for me, an incredible relationship with the Cubs, WGN, Comcast SportsNet and my partner Bob Brenly," said Kasper. "It is an honor to announce games with Bob for the greatest fans in sports and I look forward to calling many exciting Cubs' seasons to come. My family and I are very proud to call Chicago our home and there's no better place to broadcast big league baseball than Wrigley Field."
Kasper, 37, in 2009 enters his fifth season doing play-by-play for Cubs television broadcasts. He joined the Cubs in 2005 after three seasons of television play-by-play for the Florida Marlins from 2002-04.
"Len has emerged as an industry star and we’re excited about having him and Bob Brenly in the Cubs broadcast booth for years to come," said Mike Lufrano, Cubs senior vice president. "Our thanks also to WGN for helping keep together one of the best broadcast teams in baseball. Len and Bob have done a tremendous job broadcasting Cubs games and have become major participants in the Chicago community as well. We're eager to see their partnership continue to grow in the years ahead."
I think this is great. I enjoy Len & Bob and I think they have, over the four years they have been together, meshed into an excellent broadcast team. At 37, Len could be the voice of the Cubs for decades to come. We're lucky to have him.