I really like the advice in this 37Signals' blog post about writing good 'Help Wanted' ads. As with open source, the general theme is to be transparent. No hiding behind superficial buzz words and such:
The kind of help wanted ad you write can help determine what kind of applicants you get. Write an honest, thoughtful, clear ad and you're more likely to hear from candidates with those qualities. Spout a lot of buzzwordy nonsense and you'll attract people fluent in bull[potty].