Hmm, I wonder why. It is supposed to be one of those universal ones. I have just added a blouse to my cart and the coupon worked on it.
Ok, this is what it says, apparently it doesn't work on jeans:
"Today Only! Take 30% off any Gap, Old Navy or Banana Republic purchase, exclusively online. Enter RETAIL30 at checkout. Ends 8/31! (Restrictions apply.) Promo Legal *Offer valid on Old Navy, Gap and Banana Republic merchandise only from August 31, 2010, 12:00 am ET through 11:59pm ET in the US (including Puerto Rico) online only. Not valid on Piperlime or Athleta merchandise or at Old Navy, Gap or Banana Republic stores, or at Gap Outlet or Banana Republic Factory Stores or Edition by Banana Republic. Not valid at Gap on jeans, Women, Men and Maternity pants, Kids and Baby sleepwear, Design Edition shoes, Keds®, Junk Food™, Havaianas®, Converse®, Robeez®, or Medela®. Not valid on Old Navy Everyday Steals and Leather Outerwear. Not valid on international purchases. Qualifying amount applies to merchandise only, not value of gift cards purchased, packaging, applicable taxes or shipping & handling charges. Offer limited to one-time use only. Cannot be combined with other offers or discounts, including Gap Inc. employee discount. Offer is non-transferable and not valid for cash or cash equivalent. No adjustments on previous purchases. Offer subject to change without notice".