As others (Tom, Kent) already have blogged about: SQL Server 2005 Express has been released. This is as close as you can get to the beta2 bits for SQL Server. Tom lists many of the included functionality (including the XML support, CLR integration and tool integration).
Here are some additional links and tips:
SQL Express certainly gives you an earlier glimpse at the SQL Server 2005 Beta2 functionality, but it also ushers in a new era of availability of our Server and Tools platform for the hobby and student developer that goes beyond the MSDE offering of SQL Server 2000. I highly recommend getting and installing it (although to protect your system, Virtual PC may be your friend since we are dealing with a beta product).
Enjoy!