It seems very much real.

Someone once wrote me menacing to sue me because of my nickname which was infringing on some of their "IP" (I kid you not).

I did a quick check and it turns out there is a half dozen brands named something like "riffraff".

For the gnome case, just to stay in topic: http://tmsearch.uspto.gov/bin/showfield?f=toc&state=4809%3Ao...

"GNOME: hosting software for use by others for accessing weather information, for use in monitoring and controlling irrigation systems"

> For instance, could I launch an OS called CocaCola?

Yes. Edit: so long as you don't use Coca-Cola's design marks

For example, EOS is (1) a model of car (2) a sub-brand of camera (3) an operating system.

Neither Volkswagen nor Canon have shown any interest in smashing the Arista group's use of EOS.

The Gnome / Groupon example is much narrower in market scope but not so close as Phoenix ( BIOS ) versus Phoenix ( database ), which seem to co-exist OK.

No, it's real. If it wasn't, the GNOME Foundation would have not been able to trademark GNOME, since that has been a registered trademark of The Lake County Nursery in Perry, Ohio since 1980. They use it for some line of flowers they sell, I believe.

Note that the word gnome existed before the first company that used it as a product name came around. Not so with CocaCola. That word came into existence for a product, and it is also the name of the company that produces the product. That makes it a lot harder to successfully argue that using it on, say, an OS would not cause confusion.

Google launched one called KitKat, so I don't see why not. ;)

It's quite real, but there are some marks which are so well-known (like Coca Cola) that they can argue that the use of the mark in any context is likely to cause consumer confusion.

If you did launch an OS called CocaCola, they would argue that there would be some confusion in the mind of the reasonable consumer as to whether there was some association with the soft drink manufacturer.

My understanding is the outcome of the Apple Computer vs Apple Corps series of legal battles[0] was consistent with trademarks being siloed into market segments.

[0] https://en.wikipedia.org/wiki/Apple_Corps_v_Apple_Computer

No it is real, however there is another rule called trademark dilution. You can't use someone else's ubiquitous trademark, even if it is totally unrelated.

You could call your store Gnome Bikes, but you can't call it Google Bikes. Google is too famous and too unique.

There's a brand of cola called Ubuntu FWIW.