On the Careers 2.0 site, the job postings are kept for a given period of time, but after that they are deleted. It would be great if a historical copy were kept for those people who had applied for the position and the poster.
In some cases, the company may not respond before the post is taken down. Then when the applicant goes to review their cover letter, resume and job posting. The job posting link goes to the Job Not Found page.
This helps provide context for the applicant and the poster, especially when the company has posted multiple positions.