They build two different, non-overlapping products (or at least they did when I last looked into them about 3 years ago).

1) A collaborative semantic graph tool [1] -- this is the thing they're best known for. The client tool is a unified interface for both adding new information to the semantic graph as well as searching/exploring what's already in the graph. It does this in a way that scales to a fairly large number of simultaneous users and allows organizations to build and explore collective "knowledge". The input focus is on manually selecting and "tagging" semantic elements in free-text, aligning those with the system's ontology framework and even connecting together different semantic elements with certain constrained relationship types. [2] Over time this aggregates into a hihgly curated knowledge-base that can be mined more efficiently than reading lots and lots of reports and news articles.

They support a few other odds and ends (maps, various statistical tools on the semantic graph, different search methods). There's plenty of other vendors that do parts of this, but Palantir brought excellent user interface design and better collaboration tools to the party.

These days, their core semantic graph tech could probably be replicated by half a dozen engineers using HTML5 technology and some sort of scalable hadoop-like back-end in a few months. It's not that interesting of a technology. On a personal level, you could do...~70% of what they do with something like yED or Visio. Protege [3] would probably get you another 10% of the way there. A good google docs-style collaboration another 10% and so on. There's nothing uniquely revolutionary about the tech other than they brought it together in the right way.

My impression is that most of the money they make is on integrating customer data sources into the tool so users have more things to markup and add to the knowledge base. Enterprise integration is a very lucrative and time-consuming job and a competitor's quick rewrite (like I mention above) won't be able to compete against Palantir's entrenched relationship and large marketing teams. This is where most of their engineering resources are going at the moment.

2) A "big data" statistical exploration tool meant for finance. [4] I don't know much more about it other than they designed a new language for it and if connected up to the right kinds of data sources looked really powerful in the videos I saw of it in action.

They have lots of open positions all over the world, which makes me think they have lots of offices all over the world, which means they do lots of sales and marketing globally, penetrating new markets. My guess is that the huge numbers of enormous funding rounds go into marketing pushes into different verticals and locations.

They used to have a demo on their website you could play with, but they've taken it down. The tool was nice looking for 2010-ish, but it had a Java JRE requirement that was pretty old and wouldn't run on newer runtimes.

1 - https://www.youtube.com/watch?v=f86VKjFSMJE

2 - https://www.youtube.com/watch?v=l-UrRJMDGWc

3 - http://protege.stanford.edu/

4 - https://www.youtube.com/watch?v=U8YMPS_DZPk