Serviceable... not the easiest to get at, but you need to get under where the fog is and unbolt the housing from the bracket. Then you can replace the bulb, work in reverse, and you are done.
Very easy, it takes a 14m socket, Philips screwdriver and 15 minutes. There are a couple of write ups on this one so look around. It is an H2 bulb. Here you go. http://www.mazdas247.com/forum/showthread.php?t=98860
Careful, if you have rust (which is likely) you're going to want to soak the bolt with a lot of PB blaster before attempting to break it loose. Good luck!