I've never seen anybody claim a standard in this structure, but I have seen a few developers (and IDEs such as JBuilder) organize projects in a similar way. A
test directory is also not uncommon.
If you really want to get organized (and impress those around you), you may want to head on over to
The Object Oriented Scripting Forum and ask some questions about learning
Ant. I know some of those automated project building guys are big on standard (though personalized) project directory structures.