Is this still being actively developed? I would be interested in understanding how this works with POS/POW? Are there still known attack vectors that could undermine security of the network? Maybe you already had a discussion about it but I didn't want to look through the whole thread.
Yes, there are tons of things going on. ICOs are being built upon the Skyledger, miner in the works, hardware wallet in the works, etc...
The telegram is very active.
https://t.me/SkycoinHere is a good article that talks about Obelisk which is the consensus algorithm that is used.
https://blog.skycoin.net/statement/obelisk-the-skycoin-consensus-algorithm/