The latest big news for Square is Visa coming on board as an investor. This no doubt gives the mobile credit card service a boost of credibility and warning shot to potential competitors that it is here to stay. What's in it for Visa? As Forbes explains they get a piece of the action when it comes to really small business who normally use cash and are switching to credit cards. Square is a fantastic solution for people with a small side business that perhaps use it for small dollar amounts and use it somewhat infrequently. Square does not accept Amex nor can it deal well with larger dollar amounts on a daily or monthly basis (as explained here). It also does not work with a blackberry. For those who are serious about accepting credit cards they should be seeking a merchant service provider who can provide software and/or hardware for your smart phone but stay clear of contracts and termination fees.