Google will begin rolling out the mobile friendly update today, as they confirmed yesterday. Despite Google telling us you may not notice the image until the update rolls out over the course of a few weeks, SEOs and webmasters are manually and automatically checking the Google mobile results for changes.
I personally am checking some popular ones as well, so I can know when the push started.
I also know that SearchMetrics and MozCast, amongst others, have automated tools looking for the update as well.
It is somewhat comical watching the forum threads, for example WebmasterWorld has SEOs and webmasters saying things like, I see nothing yet, nothing in my sector, etc. Here are some quotes:
Midday UK - nothing happening here on the terms i've checked in various different niches
tick tock, tick tock.nothing in US yet ... waiting ...
No change here at all for my searches in the UK, informational sites.
It will happen, sometime today, and trust me, you'll know.
So sit back and relax for now.
Forum discussion at WebmasterWorld.
Update: Google announced it is now rolling out and can take about a week, while also posting their FAQs.