Trademarked terms are allowed to be added to PPC advertising campaigns through Adwords (still). The TM identifier will help reduce user confusion when trademarked result in disapproved ads.
There does appear to be some inconsistency in the trademark identifiers. Not all trademarks show up with the TM identifier, but we assume this will be fixed after some time.
We did a search for an obvious trademarked term, and you will see the new TM symbol in the image below--taken from the Adwords Keyword Planner.