The mobile versions focus on the player-facing features of the application.
Popular virtual roleplaying game tabletop software Roll20 is now available for iPad and Android platforms. Designed to facilitate both in-person and online play of roleplaying games, Roll20's tablet app caters specifically to the player side of the experience. Players can use the Compendium, Journals, Dice Rollers, Character Sheets, and some other features of the service via the mobile app. While the app can obviously give you access to existing campaigns you're playing in, GMs can also print out a QR code that gives you instant access to their campaign notes on a scan for convention games. Further, the full text chat is accessible from the App, letting players communicate secretly with the GM and each other.
If you're not familiar, Roll20 has been around for a few years now, enabling gamers separated by distance to enjoy the power of roleplaying games digitally instead of in person. Boasting 800,000 users, it's definitely a leader in the field. It's also system agnostic, so it runs pretty well with near-any roleplaying system you prefer. The full version includes maps, digital miniatures and tokens, as well as a unnecessarily complicated random number generator for dice rolls.
For more information, go check out their website at Roll20.net.