I want to clear up some misinformation on this thread.
First off, Android porting is not very far along for the TP2. Last time I checked I'd dare say it was (and this is a generous estimate) 40%. None of the hardware is supported naively yet. I.E. there are no drivers yet. You can't even get sound or data without doing some little hacks on top of the installation. Camera, light sensor, graphics card, etc are all not supported yet. You can basically just make calls, but you can't hear anything and they can't hear you.
Secondly, Sprint is trying to phase out the old SERO plans. You are grandfathered in forever, but they try to force you out by blocking the phones you can activate on the network. Touch Pro 2's are fine, but there is no "luck" involved with activating a Hero. They specifically and purposefully block it.
You cannot activate a Hero or most modern smart phones on the older SERO plans.
Doesn't matter how many customer support people you talk to.
However, you CAN use a Hero or any CDMA device on the Sprint network including a SERO plan. Notice the difference in my wording. Bottom line, it is possible to get it working, but as far as I know, it's not legal and it is a rather tricky and involved process.
For those of you who know what you're doing and really want to do this, I'll give you a hint: Google "ESN Swapping".
Cheers
