How can I upload photos from iphone/Android to Drupal?
phonegap and titanium are probably considered easier than for example, developing a separate native app for iOS and Android. 

However, if you are looking for something even easier, perhaps you could explore using an existing application that uploads images to a service such as Flickr. A query for iPhone apps on Flickr's App Garden provides plenty of results. You could then use an app such as this one to upload images and then use Flickr's API to create image galleries in Drupal. Plus, you can make calls to Flickr from Drupal and receive data in different formats including JSON and XML. It really doesn't get easier than that.

The Flickr contrib module could then provide you with plenty of examples of how to query Flickr's API.

The fact that your images would be hosted by a third party could be seen as good or a drawback, depending on how you analyze it.