I don't see anything available yet and the announcement is light on details. Hopefully there'll be something concrete before the end of their infrastructure week?
Specifically, the Workers Runtime was built as an integrated component of the overall Cloudflare stack. We'll need to detangle it a bit into something that can run stand-alone. It's important to us that what we release is actually usable.
The two specific things we aim to enable with this are:
1. Testing Workers locally (with more accuracy than our existing simulator).
2. Running your production app on your own servers (with no dependency on Cloudflare).
(I'm the tech lead for Workers.)
We still have some work to do to get the runtime ready to open source and make it broadly available, but happy to answer any questions we can.