Flat design. Apps that have skeumorphic elements are old news, the new design “style” is Flat. Not to say that skeumporhism doesn’t have it’s place – you just need to do it right.
Drag down to refresh. Lots of apps are doing this, and it’s because users have been “trained” to do so by iOS.
Hidden controls. Lots of apps are creating “trays” that expand to show navigation buttons and settings controls, which allows the user to not be faced with persistant controls that are seldom needed (and take up valuable content space).
Not design trends, but a couple of feature/functionality trends:
Social. Every app is tied into social networks and sharing nowadays, even apps that don’t make any sense to provide such a feature.
Syncing. Lots of apps are now syncing and saving data to access when the user is “off-line.”