Discussion about this at stackoverflow - http://stackoverflow.com/questions/563600/can-i-get-to-work-in-powershell
Jeffery Snover said to request it here so here I am :D
Here is a description of what they do -- http://www.gnu.org/software/bash/manual/bashref.html#Lists
An AND list has the form
command1 && command2
command2 is executed if, and only if, command1 returns an exit status of zero.
An OR list has the form
command1 || command2
command2 is executed if, and only if, command1 returns a non-zero exit status.