As discussed in the comments on http://docs.codehaus.org/display/MAVENUSER/NMaven+Project+Directory+Structure
When NMaven packages a project, it should automatically exclude the tests.
According to Shane, the command line currently does this and is configurable, while the NMaven Addin uses a hard-coded value. (Need to confirm.)
These should be aligned and both should use the same configuration. (Is <testSourceDirectory> appropriate? What about resources?)
I suggest "Tests" for the convention, since VS tends to use plurals (References, Properties...)