I recently made an effort to clear up the definition of an electric bike (there are two definitions in California).
I read all the california vehicle codes related to e-bikes/scooters, but also found a great link that summarized.
http://www.electricvehiclemall.com/pdf/CAVehicleCode-scooters.pdf (California only)
http://www.electricvehiclemall.com/scooterlaws.htm (each state listed seperatly)
Let me summarize
These are the little stand up scooters made by Schwinn and similar.
Electric and gas are in the same catagory.
Max speed is 15MPH
Can ride in bike lane.
Limited to roads with max speed of 25MPH.
Must be 16year of age or older.
Must ware a bicycle helmet regardless of age.
Motor: No specs
Age: 16yo or older
License plate: None
Can ride in bike lanes, but not on side walk
Motorized Bicycle <1kW, Class B (CVC 406b):
This are like the Xtreme XB series
Electric only. (Gas would be Class A)
Must have working pedals.
Max speed: 20MPH
Motor: <1kW (federal and state law both say under 1HP, but california interprets that to be 1000W, and federal law interprets that as 750W)
Age: 16years or older
License plate: None
Can ride in bike lanes or on bike trails.
Motorized Bicycle Class A 1kW-2kW(CVC 406a)
Like the EVT4000
Max speed is 30MPH
Helmet: Motorcycle type
Age: need to be old enough to get M2 license (18?)
Registration: None, but one time title transfer fee of $18
License: M2 motorcycle license (small bikes). Or could use M1 motorcycle license (big bikes)
License plate: Special plate like motorcycle but with no annual sticker
Can ride in bike lanes.
Also note that I found what I think is an error on the DMVs form REG230. To register your motorized bicycle is requires <2kW and "must have pedals" or else its a motorcycle. This is incorrect. Class A ebikes do not require pedals if electric as apposed to gas. Class b requires pedals, but would not use this form since class b does not require a plate.
DMV Form REG230 (to get a plate for your class a ebike) http://www.dmv.ca.gov/forms/reg/reg230.pdf
CVC 406 http://www.dmv.ca.gov/pubs/vctop/d01/vc406.htm
Same as gas.
Mo max speed. Can operate on any highway that the bike can keep up on.
M1 license required
Full motorcycle helmet required
License plate with annunal registration and sticker required