Charging for premium features - Sure. But the basic version will remain free according to the Trello Guide.
Free... for how long?
Trello is free forever. We may add pay-only features in the future, but everything that's free today will be free tomorrow and forever. Also, we'll not make a for-pay feature that forces you to compromise on privacy, security, or portability. Those are built-in. [...] Trello is free.
Forever is such a strong word... What if Fogcreek goes bust one day? I would actually prefer companies to charge money for such services, it gives greater confidence in them in the long run. Even a measly $10/year per user is a great business model if you have 1M users.
I actually don't mind HN taking a while to load. It't not that we have to fight for every new user by aggressively optimizing page load time. Btw. the recent changes to the HN backend already improved the average speed a lot.
Not to say that this valuation indicates a bubble but I find it interesting to compare it to the Moorhuhn Game Series which was popular quite a few years ago. Seems to have been the equivalent of Angry Birds in the early 2000's.
Propelled by the game's popularity, its Bochum-based publisher Phenomedia AG, who had acquired Art Department, went public in late 1999 at the height of the dot-com bubble and attained a market value of up to one billion Euro.