I was talking with a buddy of mine today about the usage
database in SharePoint 2010.  It is by all appearances a set of
partitioned tables in SQL Server.  His very good question was
well, partitioning tables is only available in the enterprise
edition of SQL Server - what happens if I have a different
flavor of SQL that I want to put my usage database on?  So I did
a little snooping around and it turns out that while the usage
database has the appearance of partitioned tables in SQL Server,
it really isn't.  Meaning it doesn't use the partitioning
features provided by SQL Server exactly for reasons like this. 
Instead, SharePoint manages all of the tables and data loading
so that it carries some of the same features as SQL partitioning
but without requiring the overhead of the SQL Enterprise SKU. 
Hopefully that satisifies the curiousity of those of you who
were wondering the same thing.