Here's what the install log tells me:
2012-08-14 11:56:12::INFO::engine_validators::425::root:: Successfully created temp database on server cmcd-web. 2012-08-14 11:56:12::INFO::engine_validators::443::root:: Checking that uuid extension is loaded by default on the remote server 2012-08-14 11:56:12::DEBUG::common_utils::350::root:: running sql query 'SELECT uuid_generate_v1();' on db server: 'cmcd-web'. 2012-08-14 11:56:12::DEBUG::common_utils::286::root:: cmd = /usr/bin/psql -h cmcd-web -p 5432 -U ovirt -d ovirt_engine_test -c "SELECT uuid_generate_v1();" 2012-08-14 11:56:12::DEBUG::common_utils::291::root:: output = 2012-08-14 11:56:12::DEBUG::common_utils::292::root:: stderr = ERROR: function uuid_generate_v1() does not exist
So, the installer is trying to create a database "ovirt_engine_test" and succeeding. But until you run `psql -U postgres -d <database_name> -f /usr/share/pgsql/contrib/uuid-ossp.sql`, the function uuid_generate_v1() won't be available. Therefore, the temporary database the installer is using to determine compatibility fails.
The problem ended up being that the postgres role which ovirt is using needs to have superuser privileges. Once I granted superuser to the "ovirt" role I created, all worked well. ~irl