1. Why junior level? Because I don't want to add memory leaks trying to add features to mongrel2, I'm not enough of a ruby wizard to hack on Rails or Sinatra yet, etc. When I start a project, I want to be doing stuff that will challenge me, but I can still get something done on. When I am hired, I don't think they're going to put me in charge, I think they're going to assign me small things to work on until I learn more and prove myself.
2. My full time job is looking for work. I have many part time jobs, like freelancing, helping my family, farm work, etc. I want to contribute so I can learn. Starcraft will not make me any happier a year from now, or even a month from now.
I use lots of open source. I spent most of a day once optimistically installing what I needed to build Firefox, only to read how long it takes even on quad-core meat grinders. I have a single core 2005 vintage laptop.
In short I don't care if I don't care about the project. The goal is help the job search, sharpen my skills, and maybe contribute something while I'm at it.