As Twitter moves toward maturity, its principle creator, tech wunderkind Jack Dorsey, has shifted his start-up acumen to a new company called "Square." Dorsey officially unveiled the project on his Twitter account on Tuesday. The idea is to allow people to accept credit card payments over mobile phones with a simple "square" plug-in device. Even though it will only be testing in a few locations until 2010, the project has already attracted enormous attention from the business community and of course, the blogosphere. Here's why everyone is excited about Square:

• It's Already Worth a Ton of Money TechCrunch founder Michael Arrington reports that while Square started with $10 million in funding, the company is actually worth "$40 million or more," even before publicly launching.  He thinks it reflects more than a growing faith in Twitter's founders: "This is a bold foray into a huge, and complicated, market: physical payments. 'What PayPal was to eBay, Square is to the real world,' said one person close to the company. Visa, Mastercard and American Express have all agreed to allow Square to take payments. This is notable because, like PayPal, Square allows anyone to have a virtual merchant account and take payments directly."

• It's Simpler Than Twitter ShortFormBlog's Ernie Smith is delighted that Square is an easy-to-understand project compared to Dorsey's last endeavor: "It’s a tiny square. It requires an audio jack. That’s it. Like Twit­ter, it’s dead sim­ple. Unlike Twit­ter, it’s not a super-esoteric con­cept at the out­set, beg­ging peo­ple to fig­ure out why it’s nec­es­sary. It just makes sense. Kudos. Could some­one give us a rea­son to use this?

• It's More Nimble than the Competition GigaOm blog founder Om Malik  is confident that Dorsey's new brainchild has what it takes to outshine similar services already offered by more established companies: "My view is that Square (or something like Square) is going to disrupt the businesses of companies such as VeriFone and Symbol, a division of Motorola that makes point-of-sale devices. Verifone makes a $900 wireless credit card terminal vs. Square, which runs on a $299 iPod touch. I rest my case. Will Square (or another Square-type company) be a success tomorrow? Probably not! But in a few years, the sheer economics of it is going to turn the tide against the dedicated hardware makers."

• It's the Future (and the Present) True/Slant's Bill Barol believes that far from being just the latest fad gadget, Square is a socioeconomic watershed: "The most intriguing thing about Square, though, at least so far, is the conceptual leap that Dorsey may have been uniquely qualified to make: Payment transactions are a kind of social interchange. If Square can bring the polish and cachet of some of the better social-media apps — apps like Birdhouse and Tweetie — to the world of payment processing, it can unlock something huge, and potentially hugely profitable. This’ll be fun to watch."

• It's Got Alyssa Milano! Bloggers were amused and intrigued to learn that one of Square's top advisors was none other than lithe Hollywood actress Alyssa Milano, best known for her roles on the TV shows "Who's the Boss," and more recently, "Charmed." "Not all of Square's 'advisors' are Hollywood sexpots," quips Nicholas Carlson at the Business Insider. Meanwhile, Wired's Eliot Van Buskirk takes a more serious look at her credentials: "Milano’s qualifying experience for advising Square, according to the announcement, includes her presidency of the web design firms Celebrity Loop and InterSports, her Touch clothing and jewelery line specializing in creating junior women’s sizes of athletic jerseys, and philanthropic work including with UNICEF and The Global Network for Neglected Tropical Disease Control. (Square donates one cent of each transaction to the charity of the buyer’s choice.)"

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