Does MySQL 5.0 have Sequences?

No. However, MySQL has an AUTO_INCREMENT system, which in MySQL 5.0 can also handle inserts in a multi-master replication setup. With the --auto-increment-increment and -auto-increment-offset startup options, you can set each server to generate auto-increment values that don't conflict with other servers. The auto-increment-increment should be >= the number of servers, and each server should have a unique offset.