tl;dr
Upgrade for London, yes you!
The hotly anticipated upgrade to Ethereum mainnet — London — has a fork block scheduled, and mainnet client releases are out. As mentioned before, to allow for validator deposits, the beacon chain validators come to consensus on the state of the proof-of-work chain and process deposits sequentially from there.
To maintain this link, all mainnet validators must upgrade their proof-of-work nodes (often called the “eth1 endpoint”).
Please see the London announcement for more details.
Warning
Due to an issue uncovered last week on the Ropsten testnet (see restrospective), Go-Ethereum (geth), Nethermind, and Erigon have cut new, critical releases as of late last week. If you upgraded your proof-of-work node prior to these releases, you must upgrade again to remain in consensus after London.
The London fork is expected between August 3-5, 2021. There is no time like the present — upgrade now!
The Merge — checklist and draft EIP
Mikhail, Tim, and I put together a public facing “Merge Mainnet Readiness Checklist”. This documents the various tasks required to get us from here to the Merge, aiding both client team coordination as well as providing a better view into progress for the community. Note that this list is pretty high level, and that it’s meant to serve as an aid. Much of the more nitty gritty organization and communication around each point happens on calls, discord chats, independent repos, etc.
Additionally if you want to get more technical, Mikhail, Vitalik, and I just released a Merge specification for the execution-layer perspective in the form of a draft EIP. This doesn’t contain any major surprises but is a critical step toward the next wave of Merge development!
Altair progress
Altair, the first major upgrade of the Beacon Chain, is making excellent progress after the launch of two small devnets primarily composed of nodes and validators run by client teams. With these first devnets, we moved from alpha to beta releases as the feature-set has been vetted by all teams with all expected refinements now in the spec — v1.1.0-beta.2 Mach’acuay.
This week, we expect to see another devnet launch followed by discussions for picking a date to fork Pyrmont, a long-standing beacon chain testnet. This will bring in many more node operators at much larger scale and set the stage for a final wave of testing and a selection of a mainnet target launch date.
For more background on the what, why, and how of Altair, check out this excellent set of Altair PEEPanEIPs by the Ethereum Cat Herders:
- #34: Altair – Accounting reform with Alex Stokes
- #35: Altair Beacon chain upgrade with Vitalik and Danny
- #38: Altair in Teku with Adrian Sutton
Lastly, prepping the Beacon Chain codebases for their first upgrade has been a fun, yet challenging task. Here’s a huge shoutout for all the excellent work by client teams to get us near this major milestone 
