It depends how you define "author". Personally I would say that at this point OpenSSH has two authors -- markus and djm -- and a number of minor contributors. Looking at 'cvs annotate', I see that markus committed 42.6% of the LOC and djm committed 32.8% of the LOC, while nobody else was higher than 6.3%. Sure, LOC isn't a very good metric, but within a single project, with everybody using the same language, a 5x gap is significant.
If you look at who is currently working on OpenSSH, the numbers are even more dramatic: djm is responsible for over 80% of the LOC committed in 2010.
direct commits, not including ok's on reviewed code:
from the last openssh announcement (http://marc.info/?l=openssh-unix-dev&m=128256356229601&#...):OpenSSH is brought to you by Markus Friedl, Niels Provos, Theo de Raadt, Kevin Steves, Damien Miller, Darren Tucker, Jason McIntyre, Tim Rice and Ben Lindstrom.