The guide books should be just fine. Ditto the data book. Any changes in the trail from their publishing date to 08 should be negligible and easily navigated on the fly.
A note on Yogi’s info (at least the town parts of Part 2): Note that she has info on small town business locations and the like. Even though the information was correct when it was collected and printed, things can change quickly in the small towns as shops open and close. Take the information as an indication of what you may find, not as what you will find, especially with respect to specific businesses. Specific examples I can think of from my 06 experience are the hotel specifically mentioned as hiker friendly in South Lake Tahoe had converted to dive apartments and the laundry in Etna had closed. Check her site for updates - I think she puts them out.
That being said, I found Yogi’s town maps and water source reliability comments to be quite useful and well worth the cost and weight.
Bottom line: you should be good to go as is.
Token Civilian