Rsync is very useful, I don't have to copy all files in a directory. It updates only the newer files.
I use it with cygwin but I think there are some inconsistencies, which are not the main focus of this question.
so is there an equivalent?
Although not an exact equivalent, and not a Powershell feature, robocopy can do some of the things rsync is used for.
See also http://serverfault.com/q/129098