Not that I know of, at least in terms of the common unit test apps.
There have been some posts to the NUnit list saying that NUnit itself might
support .NET CF in 2.3 or 2.4 (they have a solid 2.2 beta out right now; not
sure when 2.3 or 2.4 are planned).
There's a port of NUnit 2.0 that works for CompactFramework; if you Google
for NUnit.CF there's a couple of forum entries that give a link to the zip
file.