I haven't looked too closely at this transaction, but here's some info on how normal fees are calculated: http://bitcoinfees.com/ Very new and very small transactions are charged extra to discourage spam.

As noted at the bottom of the article, each miner really gets to set their own fee, below which they will just ignore transactions. But the "satoshi client" is the default and most other clients mimic it.

Edit: one of the comments mentions that "multi-sig" transactions are more expensive, and I don't know how to explain that part.