After spending awhile keeping ebuilds up to date in Bugzilla and on my own local overlay, and filing bugs upstream, I gave up on webktgtk and Midori. The former because I kept running into compilation errors; they just don't do much automated testing of nightly builds, and more importantly, Midori is still a really unstable POS at the moment.
Now, webkit was nice because it has the fastest rendering I've ever seen, period. FF3 can't match it, and neither can Opera. And I liked that it was extremely CSS compliant; Acid3 for the win. :)
But the only browser that can really use it is not even at an alpha stage, and has basically no features aside from tabs and lots of guaranteed crashes.
I also mostly used Midori to get proper integration with my gtk environment, but FF3 negates that advantage Midori had over FF2. Oh well. Midori is still an interesting project, so I'll be checking in on it from time to time in the future. I'm interested in any and all featureful gtk browsers that do webkit. :)