We've been working on our smart contract system since Hive began :-) I posted about a few of my ideas for it back then: https://hive.blog/hive/@blocktrades/hive-s-future-as-a-2nd-layer-blockchain-network
Update: actually reading post in the above link, it didn't actually talk about smart contracts directly, it just focused on a few of the foundational ideas of HAF itself. I did post a little about the smart contract side later, but in a good demonstration of why we need better search, I'm not sure which posts in the past talked about it :-)
Anyways, HAF is the foundational layer for it, so that's where we've invested most of our coding effort so far (especially as the HAF part helps with other technical challenges besides just smart contracts).
We've also done a little iteration on the next stage ideas here, but lately several of the key guys have been tied up with other issues (ABW on hived optimization, Marcin on semantic search and general HAF base layer improvement): https://gitlab.syncad.com/hive/smarc/-/merge_requests