Twitter and American Express have just announced a new program that will allow users to make purchases inside of Twitter by simply tweeting out specific “Buy” hashtags.

Here’s how the hashtag-buying works, after you sync your Amex card to Twitter of course.

Cardmembers tweet special product #hashtags for the product they want to purchase with their synced Card. Cardmembers then check their Twitter mentions in the @ Connect tab for a response from @AmexSync containing a confirmation #hashtag. Tweet the confirmation #hashtag within 15 minutes of the response from @AmexSync to confirm the purchase.

And the product(s) should arrive on your doorstep via 2-day shipping.

The hashtag-buying will officially kick off Wednesday at noon ET with these specific products:

$25 American Express Gift Card: $15.00; Amazon Kindle Fire HD: $149.99 plus tax; Sony Action Cam & Waterproof Headband Mount: $179.99 plus tax; Urban Zen Bracelet Designed by Donna Karan: $80.00 plus tax; Xbox 360 4GB console with a 3-month Xbox LIVE Subscription and 2 game tokens: $179.99 plus tax; Xbox Controller: $29.99 plus tax.

“Based on the initial success of Amex Sync for offers, we know there is significant power in combining our assets with Twitter’s platform to bring value to Cardmembers and merchants,” said Leslie Berland, Senior Vice President, Digital Partnerships and Development at American Express. “Now, we’re leveraging our unique technology and closed-loop network to introduce a seamless solution that redefines what’s possible in the world of social commerce.”

Amex has partnerships with Twitter, Foursquare, Facebook and other networks that leverage synced accounts, but until now these have only been used to unlock discounts or purchase credits. This is the first time that social media users will be able to initiate an actual purchase with something as simple as tweeting out a hashtag.