I've been experimenting with those $10 sticks on ARM but not android. Rather just linux and windows.
Though still a novice at this, I've noticed there are two basic ARM models. Some ARM devices depend on the GPU to do the heavy lifting. Other Arm chips have a native DSP, which ARM calls NEON. If you want to SDR on ARM, the NEON based chips are the way to go. The TI OMAP is an example, which is found in lots of tablets. You need to set compilation flags so that the NEON and a few other features are used for the native DSP. I'm not ruling out some clever programmer using the GPU for signal procession, but the NEON scheme makes more sense to me.
But replacing scanners is still a ways off. You can run a scanner on 200ma without doing much engineering. These SDRs are very power hungry. So the SDR is good for a bench setup, but not very suitable for portable use. Also, the SDR front ends are "agile", which translates to no filtering. Thus they don't work well in RF polluted environments. I'd want some sort of preselector.
SDR demod is not like most tablet apps. You are constantly processing data. I wouldn't expect the 8 to 10 hours you get from a tablet just surfing the internet.
I like the SDR fpr ADS-B. There are a couple programs that do the decoding, and Virtual Radar Server will map the aircraft. You need a PC anyway, so the $10 stick is quite competitive with the $500 mode-s receiver. If some clever person could demod all the ACARS channels simultaneously, that would be great. These SDRs have IIRC a 2MHz bandwidth, so you see a lot of spectrum.
On my list of things to test is running DSD MBE. These single board computers like the Beagleboard and Panda can be outfitted with LCDs and such, though at some point you are better off just taking an Android tablet and loading linux on it, or I suppose going the next step and learning how to program in Android. Ubuntu and Opensuse have Arm versions of their linux.
