What's changing?
As of today, the 
getServiceLinks() and 
mutateServiceLinks() methods on 
CustomerService are available to all AdWords API users. Previously, these methods were only available to whitelisted users.
Using this functionality and the 
Content API for Shopping, you can now fully automate the process of linking Merchant Center accounts to your AdWords account. Previously, you could send a link invitation using the Content API for Shopping, but you could not accept or reject the invitation using the AdWords API.
What do the new features do?
I thought you'd never ask! :)
  - getServiceLinks() retrieves the status of links between your AdWords account and  Merchant Center accounts.
- mutateServiceLinks() accepts or rejects links between your AdWords account and Merchant Center accounts.
What should you do?
If you're interested in automating the linking process between Merchant Center and AdWords, check out the 
updated shopping campaigns guide.
If you have any questions or need help, please post on the 
forum or the 
Ads Developers Plus Page.
 - Josh Radcliff, AdWords API Team
 - Josh Radcliff, AdWords API Team