Can I send Notification Center items to my iPhone using Pushover or Prowl?
An extensive search has determined the following:

There are a number of ways to SEND notifications TO Notification Center in Mountain Lion.

There are currently no hook in AppleScript to read notifications FROM Notification Center. This would be a key starting point in piping such notifications to Pushover or Prowl.

Conclusion: As of OS X 10.8.2 - no. Sorry. :(

Good luck and happy notifying!