I'm surprised this feature doesn't exist yet for the Jobs page?
I also didn't find any question asking for this already.
It would be very useful, thanks.
This has been implemented, hopefully to your liking: http://careers.stackoverflow.com/jobs/subscribe
We've talked about this in the past and have always thought that the RSS functionality takes care of the underlying need (being informed of new listings as they are posted). That said, if this gets enough upvotes we could reconsider this.
I had my facts wrong. This is actually being worked on right now!