What's the biggest barrier to participation in open source?

Personally, I never had much problems to enter FOSS back in 1995. I was part of comp.lang.forth and people were just too eager to help me. Taygeta offered me space for distributing my packages. Any errors were quickly noticed and reported - allowing me to adjust to these "culture driven", implicit standards. I was offered a mailinglist - which I took. So I can't say I found too many obstacles. Once the decision "to go FOSS" was made, the rest came - no problem. I have an email box to prove it.

Either this view is not too popular at "opensource.com" or they are quite slow to update their comments.

Ok, verdict is out: it is slow ;-)

I see one barrier to contributing to FOSS and that is time.

I don't know about you, but my todo list is typically twice as long as the time I have available to handle. Maybe I need to start working faster (or stop adding things to that danged todo list). Anyway, I feel some amount of guilt from time to time about not contributing more to FOSS than I am.

At a minimum, I do try to do a good job of feeding back test results and problem reports when I encounter issues with FOSS software. That doesn't take a lot of time, and maybe it helps those who do have the time to get focused in on the issues more quickly and efficiently.

I should say that I've encountered no barriers at all originating from the FOSS project side. Whenever I've wanted to contribute to a project I've always found the project to be welcoming and helpful. I think that part of it is a result of the courtesy that you bring to the communication process. If someone comes into a FOSS project like a bull in the china shop they are likely to meet with "barriers" but if you communicate with a project's community with respect and courtesy then that's what you will likely get in return. At least that has been my experience.