Braintree Founder On Decision To Raise Capital vs. Continuing to Bootstrap
braintreepayments.com
braintreepayments.com
1. Validation and hopefully constructive criticism of your business model by virtue of their due diligence process.
2. Network and contacts.
These two alone are often worth more than the cash.
Not to mention, a sane, documented API, and features / terms that actually make sense.
Other than Square and possibly a mobile phone wallet I can't think of many major sea changes that are underway right now.
Among others, USAePay has also made this possible for some years (not as well as braintree does), and the payment startup stripe http://stripe.com/ achieves the same result in a more JavaScript-y way.
It is getting more popular, though, I suppose.