Sprint has issued PRL 20227 for all EV-DO devices. While it has not been confirmed what the update changes, some are indicating that it enables EV-DO roaming on Verizon towers.
If that is so, with this update, Sprint now has more data coverage than any other carrier, since data roaming is free (billed at the standard data rate). To get the update, call data support to have your line flagged for update.