My brother was laid off/fired/bought out about a month ago and the first thing he immediately called me up for advice on a new compuer and he ended up with a 13" mbp... to, well, search online job listings and update his resume.
To argue Karalee's point, his old computer was over 15 years old and he has no Internet connection at his home.
However, the recently unemployed who are otherwise financially secure or who can afford it, might need a pick-me-up, something nice to get into and enjoy, which might make the task of putting one's career back on track a little more pleasant.
Of course, this isn't recommended for shopaholics and credit abusers.
Do unemployed need a Mac or PC? Yes, of course they do. I was unemployed for a few months after I graduated university and in that time I bought myself an iPod.
But if I had to buy a new computer and I was unemployed, I would buy a Mac yeah. I need Windows and OSX so I'm tied to their hardware for the foreseeable future.