Google Mobile App Analytics Public Beta Launch
analytics.blogspot.com
analytics.blogspot.com
Hopefully they also fixed the major problem with their previous analytics library which was that it only supported one reporting id at a time. (Under the hood it would correctly work with multiples but the API ensured a singleton for the top level "tracker" which then forced only one id.) This causes problems if you have multiple libraries or components who want to do their own reporting.
The previous mobile libraries were very much the minimal work to pretend they worked like web sites, which really doesn't work well. I wrote about this at http://blog.appington.com/2012/08/13/technical-differences-m...
To answer your questions, the new App Analytics SDKs (Android and iOS) support multiple reporting IDs. The new custom variables are essentially named dimensions and metrics that can persist for the duration of a session, and are much simpler to work with than the custom variables in the old SDKs.