Migration to Version 8.0.18

A dump/restore is not required for those running 8.0.X. However, if you are upgrading from a version earlier than 8.0.6, see the release notes for 8.0.6.
E.1.2. Changes

    * Widen local lock counters from 32 to 64 bits (Tom)
      This responds to reports that the counters could overflow in sufficiently long transactions, leading to unexpected "lock is already held" errors.
    * Add checks in executor startup to ensure that the tuples produced by an INSERT or UPDATE will match the target table's current rowtype (Tom)
      ALTER COLUMN TYPE, followed by re-use of a previously cached plan, could produce this type of situation. The check protects against data corruption and/or crashes that could ensue.
    * Fix datetime input functions to correctly detect integer overflow when running on a 64-bit platform (Tom)
    * Improve performance of writing very long log messages to syslog (Tom)
    * Fix bug in backwards scanning of a cursor on a SELECT DISTINCT ON query (Tom)
    * Fix planner to estimate that GROUP BY expressions yielding boolean results always result in two groups, regardless of the expressions' contents (Tom)
      This is very substantially more accurate than the regular GROUP BY estimate for certain boolean tests like col IS NULL.
    * Fix PL/Tcl to behave correctly with Tcl 8.5, and to be more careful about the encoding of data sent to or from Tcl (Tom)
    * Fix PL/Python to work with Python 2.5
      This is a back-port of fixes made during the 8.2 development cycle.
    * Improve pg_dump and pg_restore's error reporting after failure to send a SQL command (Tom)
    * Fix pg_ctl to properly preserve postmaster command-line arguments across a restart (Bruce)
    * Update time zone data files to tzdata release 2008f (for DST law changes in Argentina, Bahamas, Brazil, Mauritius, Morocco, Pakistan, Palestine, and Paraguay)

http://www.postgresql.org/docs/8.0/static/release-8-0.html