Dear community!
It has been some time since the last update on the Bitcoin feature. Thus, let me give you an update on the progress of the Bitcoin integration.
There has been excellent progress on the implementation front for this feature. The team has progressed the implementation of the StableBTreeMap, its integration in the replica code, and fixes of the Adapter so that we were able to sync an IC testnet with the Bitcoin testnet. 
So, the memory management with the StableBTreeMap, one of the large remaining items so far, is largely working. There have been some glitches observed, but, as we think, nothing too major.
The next steps now are to iron out some of the issues we have observed during these runs on the testnet and perform further runs in test environments to get sufficient confidence that everything works as intended. Then (This will be soon!) we will be ready for a first deployment on an IC mainnet subnet that we will observe and test for some time. Once the system has been confirmed to work as intended, we will open the feature up to to a public audience for testing (and developing against the API).
As a side task, another team is working on the SDK integration of the feature, i.e., managing the Bitcoin Adapter process from the SDK, including its configuration. This is crucial work that helps get the feature fully completed and allow people to conveniently implement canisters against the BTC Canister API.