[captainmuon]

I always wondered, if a company doesn't really want to protect their trademark (too much hassle), but has to, can't they just grant people a (temporary, revokable) right to use the trademark pro forma?

I remember seeing a company (something Linux-related) that had a very strict trademark policy, and they did sue people who used their logo or their name, or event something different but similar. But their web site had a form where you could just enter your email address and name, and it would say oki-doki, you may now use our trademark as you like, until we say otherwise.

[chc]

You could do that, but probably not in WhatsApp's case, assuming that aggressive trademark protection was a condition of the acquisition deal.