UUID/GUID - Mailing list pgsql-general

I found a page:

    http://www.postgresql.org/docs/8.3/static/uuid-ossp.html

Is that the only way to get UUID from postgresql?

* We are in the midst of porting a replication product to support postgresql, which relies on UUID/GUID for uniqueness
insteadof Sequences and Site ID's. 

Thanks,
O.