xUnit parsing works for me using Jenkins 1.498, xUnit 1.52, boost 1.42. I have a new project using boost 1.53 and the XML output format appears to be the same to my all-to-humanly-error-prone eye, but since I haven't yet set up unit tests in Jenkins, I'm not 100% sure the output is compatible.
As recommended in the xUnit plugin comments, I'm running the Boost test program with:
run_test --log_format=XML --log_sink=results.xml --log_level=all --report_level=no
I have my post-build xUnit step configured to parse results.xml
with the BoostTest-1.x format.
If you're still having problems, perhaps you can update your question with more details about your versions and how you generate the test output.