As part of a training project, we created a small log4j appender supporting TCP syslog and RFC5424. Most importantly, it is capable of formatting stack traces as a single syslog messages (NOT the usual bunch of multiple malformed messages). The work is based on the syslog4j implementation, which did not work for us (our fault? ;)) and so we extended this framework. Note that the code has never been used in practice by us, so there may be some risk associated – but that should be fairly easy to asses, given that the source is pretty small.
The download of the RFC5424 syslog tcp appender contains it all: doc, jar files as well as the source.
Feedback and usage reports are appreciated, please send mail to firstname.lastname@example.org (if you run into troubles, you can also use the same email address to discuss the problem!).