Microsoft is announcing this morning that the feature complete April Community Technology Preview (CTP) will be available for download today. They are also announcing that they are releasing this instead of Beta 3. They plan to continue to release CTP's until SQL Server 2005 ships.
Microsoft is also announcing a "Go Live" license for the Express Edition of SQL Server 2005. If you want to put any other edition into production you'll need to join their TAP program. I can't imagine they're going to take a huge number of organizations into that program.
(As I type this, the April CTP isn't available on MSDN yet but keep you're eyes open.)