Current ~x86 build error out and testing build 3.0 test5. I found that 3.0 was missing dep libxml2 v2.2.0 (or 2.0.0) was needed for the build and i think that would have fixed the ~x86 build as well. 3.0 compiles fine after build of current ~x86 libxml2 ebuild.
Fixed in openbox-3.0_beta3.ebuild rev 1.2