I'm pretty sure that this will work on any Cart or CMS or Forum input button - (this is for you Proxivire -as you like this kinda thing)
I've been using this trick to keep my users advised on whats going on during the wait times after they have clicked on ANY submit type button [ add onclick="this.disabled=false;this.value='Saving...';" ] to the end of the submit string -- what will happen is, if the user clicks on "Add to Basket" button it will change to "Adding" while the site stores the data prior to going to the basket summary page.
I use it all over, makes a little nifty effect for the user - mostly cosmetic, but looks darn nice!