02-16-2012 11:32 AM
Android does it. If you have WIFI turned on and are in a covered WIFI area you will use WIFI, and when the signal fails for any reason it swiches over to cellular data. When WIFI in enabled while using cell data the WIFI radio sleeps/standby, and when the tablet goes on standby the WIFI radio also sleeps.
The only power mangement Android doesn't do well, will be fixed with ICS. Till then whats needed, but none are avaliable, is a widget that you can toggle from Lte to EVDO-a because the Lte uses a lot of power.