It's been happening for years, but the results are getting more interesting. In the 737NG it starts with a GPS INVALID L/R, if that state persists for a while you'll get the GPS and GLS fail lights as well. In five percent of the flights or so I've seen the UTC time reappear on the clocks, but several hours off - that's quite impressive - so the signals were good enough to get through the RAIM logic at least momentarily. That also causes lovely false EGPWS warnings, TOO LOW TERRAIN for instance when you're on short final on an ILS or so. Since I mainly fly in that area I'm unfortunately used to it by now, but not being able to fly RNP procedures, not having terrain display and reverting to conventional navigation with ANP above 5NM are really reducing the safety margins.