Release 1.2.0 fixes a number of bugs.
Available on Maven Central and on SourceForge files.
We're almost there - version 1 will be out soonish.
JFact still has a lot of improvements to be done - but it's now the fastest and closest to W3C compliance that it's been so far.
As you may have realized by now, JFact is quite new. Release 0.1 is the current release; it's alpha quality: there are a few known issues (not all W3C OWL DL reasoner conformance tests are satisfied), and there are a few ontologies on which it works well. You can check whether you're lucky :-) I would love to hear about problems you have found so that I can fix them.
Release 0.1 is also available as a Protege plug in. It works with Protege 4.1 build 218; either as Protege plugin or as standalone, it requires OWL API 3.2.2.