XPath queries right inside postgresql. cool.

from the feature list

New Data Types

XML Support

New XML data type fully supports the SQL/XML specification of ANSI SQL:2003, including well-formedness checks, type-safe operations, SQL/XML publishing and XPath queries. Version 8.3 also includes additional functions for XML data export.

UUID

This new 128 bit type is compatible with most common GUID and UUID generators, supporting distributed application design.

Arrays of Compound Types

Arrays can now be created using compound types (types returning multiple columns for a single type, such as a table type or custom type).

ENUM

PostgreSQL now supports ENUM columns with a defined ordered list of alternatives. This will make migrating applications from MySQL to PostgreSQL easier.