Once again, Trademark, Copyright, and how it applies to us...
The whole post explains it, but the executive summary is this:
1. Trademark and copyright are two different things.
2. If its your original work, you own a copyright on it.
3. If it is a logo or other trademark, it may be copied, but its use may be retricted.
4. Posting a pattern or project file containing a copyrighted element in it is not permitted without the permission of the copyright holder, especially since the end user could extract the element from the posted file and use it in his or her works without permission of the copyright holder.
5. Posting a picture of your own work, even containing a copyrighted pattern, to describe and identify your work is likely fair use, since you are entitled to describe and advertise your own work, and it is unlikely that a picture will facilitate duplication of the project without licensing the pattern.
IN DETAIL:
To clarify (hopefully) what Redbear said, the CocaCola logo (for example) is not subject to copyright, but it is a trademark. You may not USE the trademark for unauthorized purposes. In theory, trademarks exist for purposes of consumer protection, to prevent consumers from believing they are buying one person's goods or services, but instead receiving another. It is the end use that will dictate what you can do with the trademark. For example, I can talk about Coca Cola brand soft drink until I'm blue in the face, use their logo to identify that company, or even educate consumers as to the differences between their product and my product (remember the whole Coke vs. Pepsi ads that had both logos in them? Do you think the rival company authorized the use?). If you sell a Ford Motors logo sign to your local ford dealership so that they can identify that they sell Ford brand cars, I don't think you've got a problem. On the other hand, selling a ford logo product to end consumers would be a problem, because they sell their logo on a great many consumer goods, and the use of the logo would possibly confuse them into believing that your product is associated with, or endorsed by Ford Motors. Creating a logo pattern for yourself is also not a problem, provided that it is not used in a way that would cause people to believe that you or your product are affiliated with or endorsed by the trademark holder.
As to copyright: RedBear is correct in that you own the copyright on your own work. Anything original pattern or project that you create, you own, regardless of file format, so it is up to you whether you wish to release it to the public. If you use a copyrighted pattern or image in your own work, you are limited to using it in the way it is licensed to you. For example, VectorArts allows you to load the pattern onto one computer, so that you can create woodworking projects, and allows you to carve those projects with any CNC equipment for sale. They do not allow the use of their work to create mass-production molds, or allow you to distribute the pattern file to others. This is why those of us who have used their patterns do not upload the project files, since doing so would create a copy of the pattern on more than one computer, and would allow others to use the pattern without licensing it.
Derivative works: If you create works with a copyrighted image or pattern, you have created a derivative work. You own the copyright on the completed work, but the copyright of the first image or pattern rides along as well. It may be possible to assert a defense against an infringement claim if your deriviative work is substantially different from the original. The test applied is based upon what an average person would think seeing/hearing/etc. the original work and derivative work side-by-side. For example, if I used a 1/2 second clip of a particular instrument from one song in my own song, it is unlikely an infringement will be found if an average listener would not consider it to be a major part of the song, and the original source is not readily identified by that listener. On the other hand, if I create a song such as "Bittersweet Symphony" (by The Verve), that incorporates an extended sample from another band's music (The Rolling Stones), so that the average listener asked to hum a few bars from the song would hum the sample from the original band, then infringement is likely to be found. How this applies to us: If you take a copyrighted photograph, and modify it for purposes of carving, it is still infringing (regardless of how much work use use converting it) if the average viewer would recognize that the carving and the photograph are the same image. The substantially different test depends on the end result viewed by a person, not the file formats, or the amount of labor used in converting.
Fair Use: The purpose of fair use is to prevent copyright from restricting the ability of people to communicate. Fair use is a defense to an infringement claim that allows people to engage in limited copyright infringement when it is against the public interest to enforce the copyright. For example, if I wanted to report about a film that is drawing a lot of controversy, playing a short clip from the film so that people can identify the film that I am describing, or get an idea as to the nature of the controversy, it is a fair use, however playing an extended portion or the whole film would not be. Likewise, republishing short excerpts of a longer work are acceptable if done for purposes of critique or commentary. AS IT APPLIES TO A FORUM LIKE THIS: Taking a photograph of a piece that you created with a licensed pattern and posting it on this board is likely a fair use, since you are entitled to describe and advertise the work that you have created, and unlike posting your project file, your photograph will not allow someone else to create one without licensing the copyrighted pattern file from the owner of the pattern.
I'm not exactly how much clearer I can make this.