Nit,
Sorry to hear about your situation. Couple of questions: How long have you been married to your spouse? What evidence did you take to the interview?
From reading your post, it seems as you intend to seek advise of counsel, which would be appropriated, but I have few ideas. Attempt to make an info pass with your USCIS DO. In addition to the info pass, write a letter to the Director of DO and Service Center. If possible, write two letters a month and found out what is happening with your petition...
If push comes to shove, then involve your US rep in Congress and Senator in your state. Your US spouse should be putting fire on these people on your behalf, because at times USCIS tend to mistreat immigrants, but when it comes to American citizens, fear of being exposed and sued tend to raise the stakes.
Before spending money on an attorney, attempt to resolve this matter through your own initiative. If I were in your shoes, I would show up for the interview in June 2007, and see if this interview is indeed in 2008. USCIS has a duty to resolve these matters within reasonable time frame, without causing undue stress and inconvenience to an immigrant. So, put more heat on them...