Just FYI:
Daox alerted me about this thread on Prius Chat about the first (or one of the first) private owned OEM plug-in Priuses in action.
First day with my Prius Plug-in - PriusChat Forums
Looks like the owner is already modifying his route so he can go all EV mode there, charge up & all EV mode home again.
EV range is much shorter on the Plug-in Prius than the Volt. Here's the guy's dashboard after arriving at work:
13.3 miles (21 km) travelled in EV mode (I think he kicked the engine on once because the heater was on from the night before. It ran for a minute or two.)
1.1 mile remaining
Since he can charge at work, it looks like he's got the IDEAL usage pattern for this car!
Worth noting he's in southern California too (for temperature/range purposes).