I do. V1 UUIDs, due to the generation via timestamps makes them sortable. This is a obvious boon for DB indexing.

Specifically with Postgres I use the v1mc version as it provides the added benefit of using "a random multicast MAC address instead of the real MAC address of the computer"[0].

[0] http://www.postgresql.org/docs/9.4/static/uuid-ossp.html