Is it actually enforced? Has anyone been taken to court over it?

Not in court but this is a resolution from the spanish data protection agency: http://www.agpd.es/portalwebAGPD/resoluciones/procedimientos... (in Spanish) From the year 2013, this was the first sanction in Spain (3500€ to a jewelry).

You can search for more sanctions here: http://www.agpd.es/portalwebAGPD/resoluciones/procedimientos... Search for "Articulo 22.2 LSSI" or similar

Google has recently been sending out warnings to AdSense publishers who serve content to the EU that they will receive a violation if they are not serving these cookie notices.

This accounts for the seeming uptick in cookie notices. To my knowledge, Google has not enforced this in the past.

My solution was to use CloudFlare to get geotags and PHP to serve the warning to only to those who live in the EU, but to each his own.

But the browser doesn't know why it's set. The idea of the law is to distinguish between cookies which are used for the operation of the site (e.g. login cookies) and the ones that are not (mostly advertising tracking). You only need to give notice about the latter.