Canonical, for instance, is one company that in the past has been knocked about on this issue. Developers and free software advocates have argued that it agreement, while simple and strightforward in form, actually contains what appear to be trapdoors. They're not hidden, either, as seen in Clause 6:
"Canonical will ordinarily make the Assigned Contributions available to the public under a 'Free Software Licence,' according to the definition of that term published by the Free Software Foundation from time to time. Canonical may also, in its discretion, make the Assigned Contributions available to the public under other license terms."
This makes people uneasy, because the wording "ordinarily" seems rather vague. Does that mean that in extraordinary circumstances, they'll take contributed code and release it under some other license? The second sentence is less vague and seems to answer that point: Canonical may indeed decide to release code under other license terms.
Canonical has publicly addressed these concerns before. Shuttleworth stated in an interview over a year ago that Canonical's contributor agreement is no different than other commercial vendors'.
So why bring it up again?
The issue of copyright assignment was a source of a long conversation I had with Taurus Balog of OpenNMS and Bradley Kuhn of the Software Conservancy a couple of weeks ago at the Indiana LinuxFest. It was a one of those hours-long discussions that happen in the halls of such events and I enjoyed it immensely and learned a lot.
And in that conversation, which bounced all over the map as such conversations are wont to do, I began to wonder: which is a more dangerous undercurrent? Patents or copyright assignments?
This is a question I will be pondering for a while, and hope to share my conclusions and others' opinions. Ultimately, it may be that they are both equally bad for open source and that the question is akin to asking which is more dangererous: the lion or the bear?