nxlog already has a binary transport, but it can only be used from nxlog to nxlog. There is though of having a binary transport, but that's a bit out still as the discussion is still focusing on the right way to generate the data and what tags are going to be used.
for the API, the initial focus is on trying to get a good C API that can replace the syslog() call. RedHat has a largish project that they've been calling ELAPI (Enhanced Logging API https://fedorahosted.org/ELAPI/wiki/WikiPage/Architecture ) that they are now realizing largely overlaps with the capabilities of the modern syslog daemons, so they are going though the code they wrote for that and ripping out lots of it to only keep what's needed. There is some question of if the result is still in the 'sledgehammer to swat a fly' category and so you have lumberlog working from the other direction