It is still surprisingly difficult to print from mobile devices. Users usually have to use an intermediate cloud-based storage location (e.g. Google docs) to pull print from. Even so, there are several stages to the process, and it is awkward to set up.
The Mopria Alliance is a not-for-profit membership organization intended to improve this situation by setting standards for mobile printing. Mopria printer manufacturer members are still only the founder members Canon, HP, Xerox and Samsung, but Adobe have signed up too. Mopria.org already provides SDKs and APIs for mobile device OS developers. Compatible printers will carry the Mopria logo, and users will be able to print jpg and png files (pdf and other file formats to follow) to them without needing and other apps - or print drivers. The mobile device will have to be in the same network as the hard-copy output device, but most protocols will be supported - even near field.
It is still early days. Take up by the other non-android mobile device manufacturers will define how standard this strategy will become, but the provision of a single platform for the four manufacturers concerned will make it easier for a lot of mobile users to print.