- Install the gist helper script
- Enable the Terminal Module in QuickSilver Plug-ins
- Create a new HotKey Trigger
- Hit "." then type in "pbpaste | gist | pbcopy" in the Select Item field
- Tab over to Action field, and select "Run Command in Shell"
- Save the trigger, then set whatever hotkey you want - I use Cmd-Shift-G - you might need to restart quicksilver for this to take effect
curl http://github.com/evaryont/gist/tree/master%2Fgist.rb?raw=true > gist
chmod 755 gist
sudo mv gist /usr/local/bin/gist
Now you can select some text, copy to clipboard, then hit Cmd-Shift-G to create a gist from the clipboard contents, ending up with a url to that gist now in the clipboard.