Google's Jade Wang says, "Seeing some reports of phone numbers, websites, or descriptions missing. The team's looking into it. This would have happened within the past 5 days or so. You can post your examples below. I'll come back with an update when I've got one."
Some are indeed posting examples. One person says some of their website links are missing, and that some are incorrect. Another says their site is displaying in the backend dashboard, but not on the front end. Another person says they're having the same problem.
Another says their phone number and address have suddenly disappeared, adding, "This really effects me being a taxi company as there is no longer a number available for people to ring."
As of the time of this writing, Wang has not "come back with an update".
Wang did announce a couple of new features for Google+ Local yesterday, including favorite stars on the desktop system, and a ratings adjustment on mobile.
On a semi-related note (and in light of all of the issues people are finding with Apple's Maps), Google shared this on Google+:
See something that needs updating in Google Maps? There are two tools you can easily use to fix the map for millions to benefit. Depending on your country, you can use the “Report a problem” tool to let us know something needs to be updated, or you can directly edit the Map in Map Maker! mapmaker.google.com#gmapstip