Version 0.6.0 will be released next week. Please spend some time this week upgrading your code to v0.5.10. Report any API differences at https://github.com/joyent/node/wiki/API-changes-between-v0.4-and-v0.6 or report a bug to us at http://github.com/joyent/node/issues if you hit problems.
The API changes between v0.4.12 and v0.5.10 are 99% cosmetic, minor, and easy to fix. Most people are able to migrate their code in 10 minutes. Don’t fear.
Once you’ve ported your code to v0.5.10 please help out by testing third party modules. Make bug reports. Encourage authors to publish new versions of their modules. Go through the list of modules at http://search.npmjs.org/ and try out random ones. This is especially encouraged of Windows users!