[Twisted-Python] High Level Twisted Question [Multiple Protocol Usage]

[J French]

I'm working with Twisted and getting my head around it but I still
have some general paradigm questions.

When using Twisted to create an application to run under twistd, is it
possible to implement more than one protocol?  For instance, If I
write a server which uses PB to interface with its python client, can
I then also check pop3 boxes from the same application / twistd process?

Put another way: When incorporating functionality into a server app
requiring multiple protocols (PB, SMTP, HTTP, etc.) what is the
standard way of effecting this?

Sorry for another newbie question and thanks for your time.