BitcoinPayment is a MediaWiki extension to limit spam, by requiring a small one-time bitcoin payment before a user is allowed to edit or create pages.
While the payment is deliberately trivially small for a normal user, it presents a barrier to a mass-spammer.
In order to enable your user account to edit pages, log in and visit Special:BitcoinPayment, and you'll be given an address to which to send a small amount of bitcoins.
Once you send the requested bitcoin amount to the address displayed and your payment is confirmed, your account will automatically be added to the trusted group and be afforded edit privileges.
Payments require the customary 6 blocks to confirm. However, if you send from MtGox, and don't choose the open transaction option, confirmation is instant (since the wiki receiving wallet is also MtGox).