One job advert is a very thin thread on which to hang a story of that weight.
Having worked in the Internet industry for many years I think it's much more likely that Google is looking at setting up significant private bandwidth between its data centres, as it rolls out local copies of the Google database to speed up searches and indexing. This isn't going to be dark fibre purchased for VOIP services - it's going to be used to make the existing Google network run faster and further. Their current bandwidth bills are likely to be huge - and they'll be wanting to get a better deal from their fibre providers and collocation spaces.
Don't believe everything you read in the papers, guys.