Grunt 0.4.1 is now available from npm.
This patch release fixes a number of minor issues that cropped up with the recent release of Node.js v0.10.0, most notably due to changes in the path API. If you want to use the latest version of Node.js in your projects, you should probably update Grunt to ~0.4.1 in the package.json file for those projects.
Either way, Grunt still works with Node.js v0.8.x, so you don't need to update if you haven't upgraded to Node.js v0.10.0.
In addition to the Node.js v0.10.0 changes, we used this opportunity to fix a number of other small issues, like properly handling multibyte I/O when spawning child processes and ensuring the Gruntfile name is case-insensitive. For a complete list of changes, see the v0.4.0 - v0.4.1 changelog.