Users simply need to sign in to their Checkout merchant account, go to the “Tools” tab, and click the “Promotions” link to create a promotion. Google says the process takes less than a minute. Users can specify the date and time they’d like the promotion to run, and choose from different dollar-off discounts to offer their buyers.

When you run a Google Checkout promotion, the standard Checkout button on your site will automatically update to display the discount amount and cart minimum. AdWords advertisers will also have their standard Checkout badge that appears on their ads change to show the same information.

“These promotional badges have been introduced to enable shoppers who search on Google.com to easily identify and take advantage of promotional offers,” says Google Checkout Specialist Gina Del Vecchio.

“Checkout promotions are a great way to attract new buyers, and we’re excited to make this functionality more widely available,” she adds.

Google recently made changes to its content restrictions for Google Checkout. The service now allows the sale of real estate rentals, timeshares, and day sight-seeing tours. Google has just announced a couple of other things that people in real estate might find particularly useful. For one, they have expanded upon their real estate features on Google Maps. Secondly, they are now offering a new type of ad to allow for comparisons between offers.

“Google Checkout sellers of real estate rentals, timeshares, and day sight-seeing tours must have a valid public business URL,” says Sammer Abdul of Google Checkout Operations. “The sellers may, however, choose to use either Checkout buttons or Checkout invoices to process transactions for the above allowable services based on their business requirements.”

The Google Checkout merchant help center provides a list of product categories (as well as examples), which are still considered unacceptable. Some of these are obvious (illegal goods), and some not so obvious (Travel packages and offers).

The competition is heating up among payment services, with Facebook now widely considered a potential big-player, and possibly Apple too. By not offering real estate rentals, timeshares, etc. Google is missing out on a fair amount of business. This is likely the driving factor behind Google’s decision to allow these.

On a semi-related note, Google recently announced it has made it easier to link Google Checkout with Google Base accounts. There’s a new page in the “settings” tab called “Checkout,” where you can add accounts to Checkout by entering a Checkout Merchant ID.