Some context that may not be obvious to non-musicians. Most companies in audio don't open source ANYTHING. Likely the primary reason for this is copycats. While Dropbox could open source their entire product and still get by on enterprise sales and entrenchment, musicians are extremely price conscious and have little qualms with flipping gear on a dime. Behringer can (and likely will) release a copy cat of the Deluge for 1/10th the price, and Synthstrom has made the brave decision to do this anyways.
No doubt this gives Synthstrom a huge boost to their (already very strong) reputation. But even more so this gives a huge number of developers an amazing foundation on which to start hacking and creating new devices.
(I own a Deluge and am a massive fan of the company)