Picture this.  You’re a brand tweeting about your amazing new product (as you do); wouldn’t it be great if people could buy directly from your tweet, with a simple tweet message?

Well now they can, with a new service called Chirp, from Portland-based startup SellSimply.

Brands will be able start receiving orders and payments on Twitter – all they need to do is connect their Twitter account to a PayPal account.  This will allow fans and followers to buy directly from brand tweets with a simple tweet:

@SellSimply #pay @brand $10 for shinynewproduct

It’s the KISS principle in action (keep it simple, stupid). As long as the user has Chirp-enabled their Twitter account, the payment is made immediately – with a 2% transaction fee, and a receipt sent by email.  Chris Teso, who heads up SellSimply, is building out the Chirp service with this KISS principle, with a view to offering a simple logistics and fulfilment service.  We can imagine that soon enough brands will be able to run t-commerce campaigns, as it has inevitably been dubbed, by simply shipping a box of products to Chirp’s logistics partner – and tweeting.  This kind of simplicity will go down well with brands and retailers who need to manage another channel like they need a bullet in their brains.

In the meantime, Sellsimply is using Chirp to power an active Twitter marketplace; that resembles, depending on your point of view, Craigslist/Ebay/Etsy for Twitter, or Square without the need for card-swiping. The Chirp web design suggests an aspiration for the latter.

One to watch.

Now head over to PlusOneToDownload.com from developer Davide Archetti, and see the innovative paywithatweet viral sample store model replicated with Google Plus.  Use the free service to offer people free digital content and products on the condition that they “+1″ you.  No transactions this time, the +1 is social currency for the digital sample. You can see it in action over at Kubizo, a site that does Kindle screensavers. Yes, it needs buffing and polishing to make it brand-friendly, but you’ll see the potential.

With the ability to drive buzz and power pop-up digital sample stores, we think these shoutouts-for-samples tools could be systematically integrated into product launch campaigns.  Follow-up them up with pop-up fan stores on Twitter and Facebook supporting frictionless transactions, and you have a smart next-generation framework for product launch optimisation using social media.

Thoughts?