Thanks to a lot of work by Chris Russi, there is now an official
CSLA .NET logo graphic:

and a corresponding "Powered by" logo for web sites or applications that are built on
CSLA .NET:

Note that the
CSLA .NET license does
not require any public display of this logo! But if you would like to use it to let people know that your application or site is built using
CSLA .NET, that's wonderful! :)
Chris very kindly created a range of different sizes, and you can
download the entire set in one zip file.