Tip 0 in this list of tips for a fresh WordPress installation mentions how to configure a custom uploads directory. By default, uploads go into wp-content/uploads/ folder, but you can easily change that in your administration. The tip gives to benefits for moving your uploads somewhere else:
- Image URLs become shorter (http://img.mydomain.com/2009/06/system-crash.jpg vs. http://mydomain.com/wp-content/uploads/2009/06/system-crash.jpg).
- The size of your WordPress folder will remain small. (Backups will be easier, and you can install and update your WordPress from the Subversion repository too.)
These are good, but I think there are more:
- It’s easier to share the same uploads between several sites. For example, if your site is multilingual and you use a separate WordPress installation for each language, then you can have a single uploads folder for all your translated sites. (However, there is still something that needs to be done with the database, so it has attachment data properly).