I hope you'll reconsider using regexps for matching identifiers on the command line. It makes it too easy for admins to shoot themselves in the foot. To prove my point, the docs at http://melor.github.com/poni/template-variables.html use an unanchored $find("webshop/frontend"), which would match e.g. webshop/frontendforsomethingelse.
I'd be much happier if Poni used globs, because they have way fewer magic characters, and those tend to stick out more. I've seen people hurt themselves even with the periods in DNS domain names, when used directly as a regexp pattern. You could always provide a --regex option for when the power is needed.