In Thomas Hatch's blog he says that he wants Salt to be a viable competitor to Puppet.[1] It looks like Salt's grains[2] are similar to Puppet's facter[3]; it would probably be fairly easy to write a grain that would pull in facter data, so if you wanted to use both Puppet and Salt with common data, you could.
I stumbled upon Salt because I've been monkeying around with ZeroMQ[4] and it was mentioned on their Labs page.[5] As soon as I can, I definitely want to give Salt a try.
[1] http://red45.wordpress.com/2011/08/29/salt-vs-puppet-the-lon...
[2] http://saltstack.org/ref/grains/