In response to CVE-2008-1488, APC 3.0.17 has just been pushed out with the requisite security fixes. But in the process of producing a php4 compatible release, a significant amount of code has been reverted in the merge into an APC_3_0 branch for future bugfixes.
I've spent a couple of hours unmerging my "bye bye php4" cleanups with the help of Kompare. And my sanity is simply due to the fact that I can "cvs diff -u | kompare -" to look at the resulting huge patch. But it is not unpossible that the new code merged from HEAD has regressions, so you could also apply the unofficial patch onto 3.0.16.--
I took your advice and did my own thing. Now I've got to undo it.