can this be made a generic classifieds system than just jobs?

Not sure what you mean. The advanced taxonomy menu creates a classified system from any number of different vocabularies. The algorithm for that is quite complex hence it is a separate module that can be used in any application. For the jobplus module I integrate that system with location generated from the addresses module.

Since this question was posed I have found myself working on a site in which the requirement involves the workforce but in a different way. Instead of looking for jobs, users will be looking for employees. I am presently working on a solution in which the name and number of content types which are available to the job search system are configurable, so this will lead towards a more generic system.

You can set up a search system that combines location with a single taxonomy vocabulary (rather than two or more) because I have done it here: http://autism.healingthresholds.com/therapist/us/illinois/chicago/il/cog... . This is probably closer to what you are trying to achieve. The Jobplus system combines location and category using layered taxonomies (adv_taxonomy_menu) in a way that suits a job site. For a generic classified site adv_taxonomy menu is not going to be very useful because the same categories don't apply to all classified items.

After some thought I have decided to do as this poster suggested and make the jobplus functionality into a generic listing module. I have an online campus which I want to set up that covers a whole country with classes in individual towns. I have been wondering how to solve it and then I realise that the jobplus functionality is just what I need. So I am working on creating a new module with the following module structure:
listing.module - this would provide the basic listing functionality and users would tick content types to be listing content types to which we can then apply any number of options as follows:
jobappln.module - this would enable some listing content types to be ticked as jobs so that people can apply to them
listing_course.module (or similar) - this would enable some listing content types to be ticked as courses so that people can join them. This is for courses that are actually conducted offline, but need an online booking and messaging system so we are not looking at a LMS here
listing_location.module - this would provide search using categories and the location module using this functionality
listing_address.module - this would provide search using adv_taxonomy_menu and the jobplus functionality.
Other listing modules could then be created for different kinds of listings in which there is a requirement to interact with the listing.
Of course some listings would not need to have any other functionality applied.

Anyway, just thought I'd post about it before I go ahead and do it.