There is a new process to rip sprites from ipad/android apps. I wish I were better at tilemapping though
To extract raw files from any ipad app simply rename the filetype from IPA to ZIP, and extract with winzp or winrar. (ex. doubledragon.ipa rename to doubledragon.zip). You can find doubledragon.ipa for download somewhere in the internet.
To extract raw files from the android should be same process, rename APK to RAR, and extract. if that doesn't work then you can use formatter http://www.intomobile.com/2011/07/04/howto-unpack-and-repack-apk-files/
Now you will have raw WAV files, and and OBM files.
To open a OBM file you will need a romhack utility. There is a great one here http://www.romhacking.net/utilities/515/.
Here is where the actual work comes, and you have to set all the options, such as resolution, pallette, 2d, etc. Then you have to line up the tiles. Someone on this forum http://www.explodingrabbit.com/forum/threads/ripping-images-from-obm-files.14625/#post-179002 just ripped roll from rockman for android using this same principal.
Hope this helps.