STYLETHREAD -- LET'S TALK SHOP!

I would apply to all 4 separately.  Unless it is a small company, there will be 4 different hiring managers involved and each should have their own copy of your resume/cover letter that relates to the specific job.  You don't really want to call attention that you are applying to other jobs.

Are the positions somewhat similar (i.e. all marketing jobs but with different focuses) or are they like day and night?  If they are completely different (and I totally understand if they are; I ended up doing that a lot because I have never really known what I want to do), hopefully they won't even find out that you applied to other positions in the company (of course they will if you are called to interview for more than 1 though).  Not a huge deal really, you just need to be prepared to answer questions from the interviewer about why you applied for, say, an accounting position AND a marketing position.  I say this from experience.