Yes, binary packages are available for the base system and as add-on packages built from DarwinPorts.
OpenDarwin uses yum as a tool to install and manage binary packages. The available repositories are explained on this page about yum.
Currently OpenDarwin uses the rpm format.
DarwinPorts provides an easy way to install various open-source software products on Darwin (and other operating systems). It is similar in many ways to the FreeBSD Ports Collection. At the time of writing, it contains well over a thousand packages.
You might also like to take a look at Fink, which is based on dpkg and apt-get.