I have almost always partitioned my drives (essentially, as soon as they became big enough to make it worthwhile; in my case 1GB).
Currently I have partitions for OSX; OS9; x86 (VPC); Archive (old stuff from previous computer drives); and iTunes (iTunes library and misc audio files I might be working on).
It helps me organize my world. Although I now have 3 drives in my G4, I would partition one large volume more-or-less the same way.
The first partition is fastest, the last slowest. OSX and any swap files (e.g. PhotoShop Swap file) or audio/video workspaces should go early in the partition map. Archives and backups later.
However, a lot of people work with just one large drive. It probably has more to do with how you like to organize things; it does take a little effort to insure those partitions are used properly. Are you a "hit return" kind of user or do you like more control over the environment? It is best to use a system that works like you do, otherwise you won't really use it.
Many people simply like to let the OS and applications do that for them (ie save in default locations rather than navigating to your preferred space). Now that OSX (and OS9) have good search functions it's easier to find files anywhere on a drive.
If Apple has ever recommended not to partition, it's probably in relation to things like how OSX organizes things; such as when a system has multiple user accounts (everything in the user's directory, where it's safer from prying eyes) or filevault security (it only encrypts the user's home directory).
If you're the only user, do whatever you want and use a good login password.
Whatever you do, it would be helpful if you thought about the initial partition scheme as pretty much final; it's not easy to change later unless you have some large backup media accessible.
If you do decide to partiton, think about it a little first; perhaps sketch out a few schemes on paper and try to imagine if any partitions would overflow with the sizes you've decided to create.