I'm working on a cmake port. I'm aware of the port posted a while back, which is actually minimally working, and not quite good enough for any real application...
There is quite a bit more to do to get cmake to work correctly within the OpenBSD ports tree. A few files don't install in the correct location, the paths to various objects are not quite right. In short, it needs a proper OpenBSD configuration. It also tends to insist in using gmake, and hard-coding compiler flags. This ought to be fixable. Then there's the whole issue of shared libraries and their versions. It's a bit slow, since there is quite a bit of code to build. I'm using VTK as a test-bed, in order to have some decent application to check settings. I must say that I'm reasonably pleased with the result so far. Once the initial learning is done, it's ways more pleasant to work with than the equivalent autoconf/automake/libtool... ;-)