This talk says “[Free Software] is generally everywhere and a lot of these smart devices that you buy off the shelf most likely is running some sort of free software but most people would never know that. Generally it’s not indicated anywhere that it’s running any type of free software. There’s no written offer for sources which is sadly the most popular… the written offer for source code seems to be the most popular way that they go about distributing the software but generally they don’t follow up with it or what they distribute is not really that.”
This article mentions that “I’ve been on a mission in recent months to establish just how common and mundane GPL violations are. Since 21 August 2009, I’ve been finding one new GPL violating company per day (on average) and I am still on target to find one per day for 365 days straight.”
I’ve got a robot vacuum cleaner that runs the Linux kernel and Busybox but came with no written offer for source code. (Per the article above, I’ll refrain from naming and shaming the company.) I might go look at the documents that came with my smart phone a little later and see if I can find any written offers for source.