Is there Split Pane support in Gedit?

In gedit, choose Documents > New Tab group or Ctrl+Alt + N your gedit will split vertically. And you can drag tabs.

Update: Gedit has now added this feature. I'm keeping my answer around for those using older versions of the application.

Gedit does not come with this feature.

But there is a plugin you can get: http://live.gnome.org/Gedit/Plugins#line-505

Not yet, but it's in development see here, someone's working on it (among other features) as a GSOC project as far as I know.