I'd go for the 07 to get the Easton frame and fork. The Aksium wheels are nicer, but not enough to justify going for the 08. Although, if you want a nicer looking bike I think the 08 is much more classy, I'm not a fan of the LOUD grean on the 07, and the Aksium wheels are very nice looking (you have to look closely to see that they are not Ksyrium SL). The 08 looks a lot like my 05 JtS which I love.
Kona's not the only manufacturer going away from Easton. Rocky Mountain has also started moving away from their long time relationship with Easton. I'm thinking there just wasn't enough (or any?) performance/weight advantage to the Easton tubes to justify the cost.