Increasingly, I’m seeing this with a singular verb: Social media is …, Social media has …
While the phrase can logically be regarded as a singular concept encompassing different components (LinkedIn, Twitter and their ilk), I still don’t like it.
Why? Media is a plural, the singular form of which is medium.
Just like data, which is the plural of datum – although I guess I can see big data as singular if it means a monolithic construct rather than the sum of its parts.
The French don’t do this better. Where we would refer to the media (and improperly use a singular verb), in French one would say les médias. Even my 1903 Larousse dictionary, which doesn’t list médias at all (not thought of as a category back then, presumably), gives médiums as the plural of médium.
The medium is the message, as a wise man once said.