"Some successful open-source companies are using a
dual-licensing scheme. In short, software is released both through
an open source version (e.g. licensed under the GNU GPL) and
through a proprietary license usually reserved to paying customers.
It's great for attracting OEM vendors since they can integrate the
dual-licensed software into their proprietary application without
fear of contamination. FUD is apparently good for business.
"But this approach has important drawbacks (some of them nicely
developed by Glyn Moody a few years ago and also discussed here by
Lajos Moczar) that make it question whether a dual-licensing model
is really fair to the community and its developers..."