Using the apache server (in-built on Mac OS X) to run Eggplant is something that I have found extraordinarily useful.
I am currently testing Windows applications, and have set up the Apache server as an HTTP Server.
This allows me to call Eggplant scripts remotely using a browser and a bunch of other things that make using Eggplant much simpler.
I would highly recommend the use of the server!
If you are not sure about how to start the server, you want to read these articles that give you step-by-step instructions on invoking the Apache server. Even if you feel you do not need to use the Server this series of articles (It has 6 parts) is an excellent read.
I have found the server useful to run scheduled tests from other computers (I need to work on supplying paramters to my CGI scripts). The best part is that it makes Eggplant platform independent in terms of driving tests. It is also very useful if you’re too lazy to walk up to the Mac machine to start your tests.