In a small company, anyone may write the user guide - we had a junior product manager do it until they outsourced the job to a technical writing contractor.
If it's between a tester and a developer - I'd say the tester is better equipped to write it - they need to know the whole program whereas the developer only needs to know their particular feature(s). Also, the tester usually uses it just like the user would. Developers tend to get technical and go over (some) users' heads - you should see some of the error messages they come up with at my work.
That being said, it also would help if the tester had some writing experience and/or education. I thought at one time I would like to try my hand at tech writing. After trying to compose a couple "how-to's" on our wiki web, I knew the job was better left to others.
Thanks for your reply. In our case, developers don't do testing. Each developer generally has one project. The tester tests all programs writern by developers. It is up to the boss to decide who is going to write.
The next step after doing documentation is user support and then user training because you know all of the application [img]images/icons/rolleyes.gif[/img] That was one of the reasons i left my last job. I hate being interupted by phone. But now i'm doing just that again.
Positive side: you get more indispensable than a simple tester.