I am not sure on the "exact" date. It was posted on the "months of miles" thread that the T&C said "not eligible on purchase of gift cards" now on the United shopping mall....but I believe this happened sometime right after Sept 9th or along those lines.

Hold onto that screen shot. I think you will need it. I have no doubt that once people start emailing about "missing orders" that they will try the "gift cards do not count" crap. Right now on Ultimate Rewards mall through Chase it specifically states you can earn them for gift cards...