Emacs GUI for Mac, linux and windows

Question

I'd like to start using emacs but I want also a GUI in which it will be available in windows, ubuntu linux (desktop) and mac osx. Is GNU/Emacs capable for this? What other choices are there and how different is for each OS?

Also is there any disadvantages of using emacs with gui (for example, I can't use some kind of widgets or use something else) and how most other programmers prefer to use emacs? I want to use it as a replacement for textmate for ruby on rails development, any other suggestions?

Answer 1

Emacs has a native GUI version of GTK+(GNOME's toolkit), OSX with Cocoa from Emacs 23+(there is used to be Carbon Emacs before that, but it's now en route to oblivion) and Windows version.

I personally use emacs in daemon mode(emacs --daemon) and use emacslient to connect terminal and X clients to the daemon. I spend most of the time in a X frame though, I find that much more productive - instead of running Emacs in a terminal like many people do, I run my terminal in Emacs. I don't used menus/toolbars - just a naked frame most of the time, split into many windows.

For rails development with Emacs you should have a look at rinari and nxhtml.