Wow, I must have hit the big time. Someone linked to an entry I wrote back in December from the University of Michigan. :-). On it, they write about my vague description of static partitioning. To help clear things up a bit I thought I'd provide a link to a Wikipedia entry with more info about logical volume management. Additionally, the article entitled "Unix/Linux Disk Partitioning Guide" written by Wayne Pollock describes reasons for wanting a logical volume manager instead of using simple static partitions.
In short, static partitions can't be changed dynamically, meaning you can't resize them. To make a new partition you need to blow them away and start over. A logical partition can be resized by adding new disks, taking over space from an existing disk, etc. I would strongly encourage anyone reading this to refer to one of the links listed above for more useful (and accurate) info.