I’ve heard VACUUM overhead and transaction wraparound can become a big problem in some Postgres installs, so it’s nice to see this is finally being addressed. Personally I’ve also run into problems regarding the tuple overhead with very narrow tables, so this looks quite promising to improve that situation, as well.
FWIW those vacuum issues are not so much a problem since 9.0.
I used to run Postgres 8.2 and those issues led to terabytes of bloat- we also had some wraparound issues too but both of those basically went away some time between 8.2 and 9.0 due to the huge improvements in vacuuming.
bit of topic, but very nice to see that a maker of open-source multiplayer game engine  is helping/sponsoring this PostgreSQL work.
Nakama officially supports cocroachdb as their underlying database (database is accessed via postgres-binary-compatible CochroachDB driver, I think). But , Nakama also supports, I guess, unofficially, PostgreSQL (and are very helpful on their forums with regards to pg users).
Isn’t there an auto vacuum that does vacuum in the background automatically?