According to a report from ESPN Chicago's Bruce Levine, Kerry Wood will retire today. Wood's struggled this year. He's given up eight hits and walked 11, while striking out only five, in nine innings. Until his hiccups this year, and, evidently, his retirement, Wood appeared set for a semi-successful twilight as a late-inning reliever. (He had the highest career strikeout rate per nine innings of any active player—and the second-highest in baseball history, behind only Randy Johnson—and he maintained it while in the bullpen.)
It's worth noting that the oft-injured Wood, unlike his oft-injured brother in abuse at Dusty Baker's hands, Mark Prior, actually had a pretty long MLB career. He turns 35 next month, he pitched for 14 seasons, started 178 games, made a couple all-star teams, all that. Only a couple years did he pitch as well as he did in his rookie season—he had his 20-strikeout game that year, for instance—but that's a function of Wood's injuries and his fluctuating luck. And, of course, despite the injuries, his career went on: he couldn't stop now, he had to finish.
Source: Cubs' Kerry Wood retiring [ESPN Chicago]