This deal is about as good as it gets, in terms of "free money" - so read on ...
This deal is a good example of how it pays to have an American Express credit card (or two, three, or more), and why it is good to have secondary/authorized users with an AMEX card (for spouses and kids 15+).
Read a great FAQ about the deal HERE, and/or on AMEX's own website for this deal HERE. AMEX's own website is also where you will register each of your cards, WHICH YOU MUST DO IN ADVANCE of this Saturday.
As you will read (above), you can basically get $10 free (up to 3 times per card - including secondary/authorized user cards) at many retailers and restaurants ... and some other surprising places you might not expect, such as some grocery stores (such as New Seasons in the Portland area).
You CAN use this deal to buy gift cards (as long as they are $10 or more), so you can effectively "bank" this deal for a later day.
This is a potentially great deal, especially if you have a decent number of AMEX cards. Granted, it requires a bit of running around (or going through the checkout line at a retailer multiple times), but $10 free (multiple times) is a good deal.
AMEX does this every year, so even if you don't have any (or many) AMEX cards this year ... there's always next year.
For anyone who might worry about this "hurting" the small business owners, as the FAQ link (above) highlights, this is put on by AMEX and other sponsors - and apparently the small business owners themselves do not take ANY hit on the $10 per swipe.