As of PostgreSQL 7.0beta3 running on RedHat Linux 6.1 (with locale disabled in the OS by removing /etc/sysconfig/i18n), I only get one failure in the regression test -- geometry.
If locale is being used, alot of the tests fail. Sometimes installing to a nonstandard directory will cause them to fail. And the parallel tests are pretty finicky.
E-mail me your regression output and diffs (regression.diffs in the regression test dir), and maybe I can help. Knowing what OS and platform would be helpful.