Update: It looks like Telstra has had carrier billing for a couple of months, and Google is just now getting around to updating the support page. Thanks to Adam Ricket (@onlineadr) for the heads-up.
Good news, Aussies: your mega-carrier Telstra is now in Google's good graces when it comes to billing for apps and other purchases on the Play Store. Just select carrier billing during the checkout process, and the purchase price will be added to your next phone bill instead of your credit or debit card.
Customers of Telenor in Norway and Beeline in Russia, you can also spend your kroner and rubles via your phone bill. Unfortunately, all three are the only carriers in their respective nations to offer the service.
There are a couple of other updates on Google Play's carrier billing support page: O2 in Germany and Movistar in Spain. Both of these are subsidiaries of telecom giant Telefónica, which previously appeared in the fields for both countries. The updates are in name only.