I know that Go is new and experimental, so I don't think that there already is one. But does anyone know one being worked on? I know that syntax highlighting is available for emacs, vim and xcode. But is there any integration into Eclipse,Netbeans or something like that?
Not presently. Give it some time, and check on the go mailing list http://groups.google.com/group/golang-nuts.
With the attention the language has received, the pedigree of its developers, and the fact that the announcement came from Google, I guarantee you that at least one is already being worked on this very weekend.
It will happen gradually, with syntax files for editors (some are already available). Things don't really get interesting until there is a source level debugger.
The best you can do now is to use a common IDE with Go syntax definitions, and tool settings for its compiler, along with settings to capture the compiler output. Granted, this won't give you debugging, but Go doesn't have a debugger yet. ;-)
Heck, only the syntax file is a bit tedious to write, but it's not a mountain of work to do. Then it's just about writing some basic code to compile with a shortcut and regexp to display the tool output. Most good IDE's have these features. Some even support jumping to a line by double-clicking it on the captured output, if the regexp is written right.
For those BBEdit users out there, I have uploaded a Go Codeless Language Module. While not an IDE, it will help make Go projects more readable in one of the most popular text editors for the Mac.
I'm working on a language pack for Notepad++, it makes the process simple enough. I just need to work out how the commands all work together.
There's a project called goclipse, which should integrate nicely into Eclipse via plugin
I use IntelliJ with the Go language plugin. This works well as an initial IDE for Go language, I'm sure the Go language plugin will evolve and improve. See my article here: http://www.philipandrew.com/?p=46