The netBook's serial devices are /dev/ttySA0 and /dev/ttySA1; you can see these at boot up time. ttySA0 is wire, ttySA1 is irda. irda doesn't quite work yet, except I've not tried powering up irda in EPOC to see if a subsequent quick boot to linux won't give irda. PPP will work over the serial ports - see the chapter on PPP from the netBook in this HOWTO. Mice can also be used over the serial ports - see the chapter on Using a Mouse in this HOWTO.
Minicom can be used to poke and prod a modem or GPS serial port, such as might be on a PCMCIA card that you've just inserted. The modem should respond with OK to mincom's initialization sequence; raw NMEA strings should be seen from a GPS device.
This section is new and under construction.
You can install minicom to check that serial port is working and communicate with your desktop.
The netBook's serial port is meant to be a maxim MAX3243-RS chip, which is a complete, robust serial port.
(DOESNT WORK YET) To enable the infrared connection, one executes irattach /dev/ttySA1 -s 1 on the netBook, and irattach /dev/ttyS1 -s 1 on the other machine (if ttyS1 was recognized at boot up of the notebook computer as the IR device). There is also likely to be a /etc/init.d/irda startup script on the notebook computer that you could use. The -s 1 flag enables system logging. Even though ttySA1 or ttyS1 are used to make the IR attachment, /dev/ircomm0 is still the serial port to use on either notebook computer or netBook. The command irdadump, which is a standard tool, can help in debugging the connection - it will show, at the lowest level, when the remote IR signal is picked up or not. NOTE that the use of IR is meant to consume a considerable amount of power; turn it off by killing the irattach process when it is not in use.
You can buy PCMCIA serial ports (check e-bay; ca. $40). Such a serial port can be used with a mouse to add mouse capability to your netBook - see the section on the mouse in this HOWTO.