Read only access currently to google plus api
Read only access to Google+
"Note: The Google+ API currently provides read-only access to public data."
The reasoning behind not supporting read & write access to the api is probably vastly different between a "Big Fish" and a "Small Fish", yet it makes it clear.
"it is okay to release an api with limited functionality."
Read only
A few methods
Its refreshing to see this being done by a high profile site as it reminds me that your product doesnt have to be anywhere near finished to the "vision in your head" before you should open/release it.
Take away advice for you and for me:
You can launch your api if any of below are true:
Before it is fully complete.
As soon as you have data to share.
As soon as you have data to receive.