From
http://www.rockhall.com/inductees/induction-process/:
Performers
Artists become eligible for induction 25 years after the release of their first record. Criteria include the influence and significance of the artists’ contributions to the development and perpetuation of rock and roll.
The Foundation’s nominating committee, composed of rock and roll historians, selects nominees each year in the Performer category. Ballots are then sent to an international voting body of more than 500 rock experts. Those performers who receive the highest number of votes - and more than 50 percent of the vote - are inducted. The Foundation generally inducts five to seven performers each year.
You have to remember that Bon Jovi won't just be up against the other performers who become eligible in 2009, but also against performers who were eligible earlier but didn't get in. We know the band has never been the darling of the critics. I think they'll get in, but I guess I'd be surprised if it happened the first year.