Yes, the City of Westlake Village has "recommended guidelines" for the operation of leaf blowers that was approved by the Westlake Village City Council on June 27, 2012.
The detailed Guidelines are available on the City's website at www.wlv.org but here are the highlights:
Leaf blowers are only to be used between 7am and 4pm on weekdays and 8am to 4pm on Saturdays. Sundays and legal holidays are banned from use of gas powered leaf blowers.
One must use leaf blowers at the lowest speed possible...if a higher speed is ABSOLUTELY needed, one must do so for no longer than two minutes.
Mufflers and air filters must be used and serviced/cleaned periodically.
One must observe wind direction when operating the blower...and must blow in the same direction of the wind (except of course if the wind is blowing into your neighbor's property, city streets/gutters or the lake, in which case you might want to stop blowing).
Actually, one must NOT use leaf blowers when there are excessive winds or when any doors or windows are open.
Bottom line: When the area to be cleaned is small, grab a broom or rake and have at it. The guidelines state that failure to abide by the guidelines "could result in legal prohibitions against the use of leaf blowers."
The neighboring City of Thousand Oaks has no such guideline. The general Noise Ordinance in Chapter Five of the City's Municipal Code indicates that no powered equipment such as "backpack blower" (not to mention lawn mowers, edgers, etc.) shall be used between 9pm and 7am. That should explain why you never hear your neighbor mowing their lawn at midnight.