To Open Source or Not to Open Source?

I have been receviving a lot of feedback on Adoppt.com and based on the feedback, I have one question:

Should I open source my project? What are benefits / drawbacks?

Adoppt employs many principles that I have learned over the years. Alongwith my upcoming Pro Rails book, it will be something nice to give back to the community.

So far I think I would like to Open Source the software only for personal use and place a licensing fee for commercial use. Is that possible with Open Source? I know MySQL does something like this.

If I do Open Source it, should I host the code myself or put it on Sourceforge or Rubyforge?

Questions / Ideas / Experiences / Suggestions Welcome

Frank