Unless you have a valid and signed job offer it will not be final. They might not hire you, just because they need someone doesn't mean they will accept anyone. If you have more contact with them and they go over your qualifications and think you are appropriate for the job, then you can do that. Personally, I think the job would be better than the fellowship, but that's only if things are certain and you aren't going to get booted out of that job in a year. If they need someone ASAP who is to say they will wait for you to finish your training - if you are only now considering applying for fellowships then you probably would be applying for no earlier than the 2009-10 academic year, and even then it's getting late to start that process.
You have to do what's best for you. Don't torpedo your future because there MIGHT be a job out there in 15 months. You can't leave residency early. It might be a crap job, who knows. It might be a great job. You can always apply for fellowships and withdraw your application up to the point where you sign a contract (and even afterwards, perhaps, if you are leaving to get a real job, in some situations).
Doing a fellowship is extra training. If you are comfortable with where your skills are without it, the only reason to do it is to get the piece of paper and the credentials. If you can get the job you want without the credentials and the paper, the fellowship becomes essentially worthless. But if that is not your ideal job and you plan to move on to a different one, it might make a difference. But if you prove to be a superstar efficient and competent pathologist at this job, you also might not need the fellowship because you have proven skills, experience, etc.
You have to make these decisions on your own weighing all the factors.
