Check their Github repos to find out.
STEEM
STEEM is the actual core blockchain code for the STEEM token. This is what matters most for this ecosystem and where all the value is really created. To understand why STEEM is more valuable than Steemit, please see: STEEM Is NOT Steemit. STEEM Is More Valuable Than Steemit.
Steemit (Condenser)
Steemit, the website, is called Condenser on Github. It's the code that creates the interface most people use when interacting with the STEEM blockchain. In many ways, it's just a reference implementation for what's possible. At the same time, Steemit, inc has committed resources to improving it and is actively developing it as you can see here.
Jussi
Jussi is a JSON-RPC 2.0 Reverse Proxy Frontend for Steemit. In non-techno speak, that means Jussi makes Steemit scale. When someone pulls up a page on Steemit, a reverse proxy allows a cache to serve up that page without having to go all the way to the blockchain data which would be orders of magnitude slower.
Steem-js
Steem.js is the official JavaScript library for the Steem blockchain. Many third-party applications (i.e. not developed by Steemit, inc) that integrate with Steem (examples of third-party applications include DTube, DLive, Busy.org, Utopian, etc) use steem-js.
Steem-python
Steem-python is the official Python library for the Steem blockchain. Similar to Steem-js, this library is used by Python developers for building applications built in Python which use the STEEM blockchain.
Hivemind
Hivemind is an off-chain consensus layer for Steem communities and API server for social features like feeds and follows. This keeps track of all the stuff that is not part of the core blockchain, but needed for the overall social media experience. When people talk about "Communities" needing to be implemented, this is what they mean. You can see the Communities Draft Spec here.
Steemconnect and SteemConnect2 (sc2-sdk)
Steemconnect and SteemConnect2 are JavaScript SDKs which most 3rd party applications use to get your permission to interact with the STEEM blockchain on your behalf. This is an important part of the STEEM ecosystem as it creates a trusted website where people can confidently enter their password without having concerns about giving out their keys to various applications. Through this approach, you can grant permissions and later revoke them without the application you're using ever knowing your actual password.
There are more projects we could talk about and view on the official Steemit, Inc Github such as devportal, imagehoster, dsteem (RPC client), conveyor (APIs), redeemer (SP Delegation Tools), overseer (User Analytics Telemetry Receiver/Multiplexer), yo (Modular event-driven notification service), and others.
Why should you care?
The reason I'm highliting this activity can be summarized in one sentance:
Put up or shut up.
It's so easy to criticize. It's much more difficult to build and create. Some (myself included) have criticized Steemit, inc, the team, or the leadership without always doing the work to better understanding what's actually going on. If your answer is, "But I'm not a developer. I can't read code to know what any of this means." Okay, fair enough, but that gets back to the "put up" part. If we have a valid criticism of anything, we should fully understand it first in order for our input to be valid. It's easy to say "They should do this" or "They should do that," but ultimately we're making assumptions unless we have enough information. Lots of information is out there on Github for those who are willing to look at it and understand it.
AND I think it's valid to expect more "official" communication from Steemit, inc via the accounts 
Beyond just the code, there's also business development going on:
I could go into more, but I think you get the idea. I had a discussion with 
In summary, let's find out how we can help Steemit, inc instead of just pointing out the issues we see. This post highlighting their Github activity over the last month is my attempt to help. What can you contribute?
This is an amazing blockchain with a solid development team, and I'm very excited about the future.
I hope you are too.
Witnesses: you can help here also. Regular communication is important for building a valuable reputation for yourself and the STEEM blockchain. Your voice matters.
