Sublime Text 2 - Default Document Type

Create a new plugin Tools > Developer > New Plugin...

Paste this in:

import sublime, sublime_plugin

class EverythingIsPowerShell(sublime_plugin.EventListener):
   def on_new(self, view):
      view.set_syntax_file('Packages/PowerShell/Support/PowershellSyntax.tmLanguage')

Save and call it NewTabSyntax.py. New tabs will now default to Powershell.

You can change the syntax to whatever you prefer. To find out the "path" of a particular syntax, simply open a file of that syntax, open the console (View > Show Console) and type:

view.settings().get('syntax')

This plugin does it:

https://github.com/spadgos/sublime-DefaultFileType

seems pretty great.

Edit:

Ok, two things, there currently seems to be a small bug so the text file syntax is not being correctly picked up due to the whitespace in the filename. In addition you need to set the "use_current_file_syntax" to false, (otherwise the new file will default to whatever filetype you have open already when you hit Ctrl-N)... So the fix/workaround is this:

Put the following code in: Packages/User/default_file_type.sublime-settings

{ "default_new_file_syntax": "Packages/Text/Plain_text.tmLanguage",   
"use_current_file_syntax": false }

NOTE THE UNDERSCORE.

Next, find the "Plain text.tmLanguage" file and copy and rename it (in the same folder) as "Plain_text.tmLanguage". [be sure to copy/duplicate it, do not just rename it, as it may have dependancies]

Restart, just to be sure, and this should do the trick. Also note this plugin only works for new files created with Ctrl-N.