We have just had word from the official S60 Browser Blog that no matter what you may have read on a few websites, Nokia is not backing out of webkit support for the S60 browser.
Peter from the S60 Browser Blog says,

“As I understand it, one of our developers did some housekeeping on the Tiger branch of the webkit project, and some people thought it looked like we were backing away from the whole open-source project. No, no, no — it’s just that we’re focusing on the newer Leopard branch, we …