There seems to be some confusion here, and since this thread is highly ranked on Google, it seems relevant to clarify.
Google has a couple of different API's to use for their maps service:
Javascript API
The old version of this API was version 2, which required a key. This version is deprecated, and it is recommended to upgrade to the newer version 3. Note that the documentation still states that you need a key for this to function, except if you're using "Google Maps API for Business".
Static Maps API
This is a whole different story. Static maps is a service that does not require any javascript. You simply call an url, and Google will return a maps image, making it possible to insert the URL directly into your <img>
tag.
The newest version is version 2, and this requires a key to function because a usage limit is applied.
A key can be requested here:
https://code.google.com/apis/console
And the key should be added to the request for the correct image to be generated:
http://maps.googleapis.com/maps/api/staticmap?center=New+York,NY&zoom=13&size=600x300&key=API_console_key
I hope this clears up some confusion.