Running out of cash is the first reason why company go out of business (nota bene: you can run out of cash and be profitable, cash != profits).
Really.. two hundred million? If you haven't made it now, I can't imagine you'll make it in the future unless you drastically change your business model. drastically!
My position is if you can't monetize your business soon after coming out of the gates, you are just living a dream.
It appears there is absolutely no real concentrated approach to monetizing Twitter's business model. This seems analogous to AT&T providing free SMS's to all customers, and then trying to figure out a way to monetize SMS's.
Thank God I don't have to even think about funding, much less multiple rounds.
How hard is it to staff a team of engineers to get that damn site to be stable when they have 10's of millions in the bank?
There has been a significant evolution in the last 3-5 years respect to building and growing a company.
Google/Facebook/Twitter/Zynga [and others] are all direct competitors.
They all vie for the same thing [time/information/attention] of their audiences. There is no difference in what energy they need from their respective audiences in this matter; thus their business execution strategy requires vast capital to maintain their current hold on the slice of audience energy in the long term.
It also plays into how they are defensible. Twitter is taking an offensive position with its platform and how it treats apps built by the community. This money will likely be used to acquire and defend itself until it irons out is business model.
Zynga has been very silo'd in how it acts (their product originality issues aside) with respect to innovation.
Facebook has an incredible committed user base that is not going anywhere anytime soon.
Thus in the next two years, we will really see a battle on useful extensions (profitable extensions) of these platforms that are all competing for the same resources of their audience (attention and time).
So these companies all are hedging against coming innovation from each other with respect to how they will garner that audience attention.
The evolution that I mentioned then, is in that the aggressive manner in which these companies raise enormous funding is all based on their understanding that they really are competition in the information state, and it doesn't matter that one seems to be in a different space or appear to currently be dependent on one another.
I think we really are on a precipice with respect to the landscape of how people will primarily consume/contribute through their preferred sites.