Let me share my findings before asking the question.
Google Places API documentation says: "Note: To use the Google Places API you must first request a Maps API client ID and cryptographic key which you must use to sign your request URLs. For information on signing URL requests, please see the URL Authentication documentation within the Web Service APIs home page."
The Google Places API is still in developer preview. http://code.google.com/apis/maps/documentation/places/
We need a Client ID (required) and a Signature (required) to use the Google Places API. http://code.google.com/apis/maps/documentation/webservices/index.html#URLSigning
And, to get the Signature, we need a Google Adsense account to get Adsense publisher id (required). http://gmaps-ws-console.appspot.com/
You can find the requirements to use the Google Places API here. http://code.google.com/apis/maps/documentation/places/index.html#Requirements
The Signup page for Google Maps API suggest that, "Your service must be freely accessible to end users. To use Google mapping technology in other types of applications, please use Google Maps API Premier. See this FAQ for more information." http://code.google.com/intl/it-IT/apis/maps/signup.html
Now, here's what i want to know.
I'm planning on using Google Places API in my iOS application. I don't want to use Adsense. Can i still access the Google Places API for free? How?
If i can't access the Google Places API for free, what are the costs associated with using this service, and the available payment models? I wasn't able to find any particular resources for this information.
Here's a specific scenario. What if my iOS application is free. The free version uses Google Places API. But... my iOS application has some additional features which are exposed using In-app Purchase (paid features). The paid features do not use Google Places API. Is this acceptable?