On whether or not it's possible for Sprint to dig up data after a complete Odin wipe may be debatable, but I lean toward supporting the "yes, they can" side. Sprint has been, for - as far as I can tell - a while, since the Moment at least, been including Carrier IQ in Android ROMs. Carrier IQ - which you can get more info on here
(browse around there) is highly invasive, to the level of being spyware. It tracks signal data, application usage, and much else - its services and libraries are tied deeply into the system, to the point that killing just the client (not the server) will destroy the battery meter.
We (ACS) made progress in rooting out Carrier IQ with SyndicateROM Shuriken and Xtreme Kernel 1.0.1, but we didn't get it completely removed just yet. We did, however, kill the 'iqmsd' service, which, if you run 'getprop', you can see automatically starts on all devices NOT running Xtreme Kernel.