Get well soon Jenson!

Oh no.. Here's an exerpt from a Honda F1 report on the start of their winter testing program (and Jenson's health):

Jenson Button is currently en route from Japan where he attended the Honda Racing Thank You Day at the Motegi circuit on Thursday. There he met some of the 26,000 Honda customers invited to a special celebration of Honda’s motorsport participation. He recently sustained two hairline cracks to his ribs whilst participating in a karting test scheduled as part of his winter preparation. As a result, Jenson will not take part in next week’s test to ensure that the condition is not further aggravated.

I hope it heals up soon. It's currently being discussed in the forums here and here.