Today reading John Resig's post about Open Source Release Syncing I thought there were some good bits in there about WHY people support open source software, especially this quote (I added the bold emphasis):
At the jQuery project I've generally split our time indiscriminately but with a sleight bias towards Free Software. By biasing towards Free Software projects we're able to get better mind share amongst developers - who are our key users. For example, getting jQuery support in Drupal was a major victory for us as it meant that all future Drupal module developers would be compelled to, at least, examine jQuery to see if it suits them well, or not. While there isn't, necessarily, a financial reward to working closely with Free Software the eventual market control will be quite significant and useful for further leverage.
I think companies like Adobe could leverage the same ideas with the goal being the same as jQuery's: market control.