Just wanted to let everybody know (if you didn't already) that there is an option built into WoW to disable the version checking and allow you to play with interfaces (at your own risk) that weren't specifically designed for the version you're using. Here is how to do it:
Open WoW and get to Character Select
Click on "Add-Ons" in the lower left corner of the screen
At top there is a checkbox for "Check Version Compatibility" - un-check it
Its better to use this method than to modify the .toc files yourself, because you will know which files are modified and which are not when you turn version checking back on.
Here is a link to the official thread on this:
Link!
Be sure to check back over the next few days to get the updates when the author(s) of your interface(s) make updates
/edit - CTMod and BloodEagle's Recompilation have both been updated thus far (15 Feb 05) - Cairenn
/Edit - Gypsy has been updated as well (15 Feb 05)
/edit again - Insomniax Recompilation up as well now too