Sublime Text 2 has a feature called Snippets, this allows for only static 'expression' + TAB replacements.
It seems someone is working on a plugin called SMART Snippets in which you can use python code in the Snippets.
With SMART Snippets, You can now use Python to dynamically create
snippets.
The python code in your SMART snippet would be something like:
###regex: no
###params: no
###trigger: today
```from time import gmtime, strftime
insert(strftime("%d/%m/%Y", gmtime()))```
This now works in my Sublime Text 2 by typing "today + TAB"