Here's my scenario:
I have three specific jobs sites: LAMPJobsLA.com, MobileJobsLA.com, SocialMediaJobsLA.com
I'd like to run them under on "master site": TechJobsLA.com but keep the URLs intact when a visitor lands on the page with the posts matching the categories or tags (taxonomy).
For example, if someone visits MobileJobsLA.com, the two URLs that would both work are: http://techjobsla.com/tag/mobile-ios-android/ or http://mobilejosbsla.com/ default page redirects to ---> http://mobilejosbsla.com/tag/mobile-ios-android
Hope that makes sense.
I see from some of the previous questions/answers, WordPress MU Domain Mapping plugin might work for me.