From the RTFM department, [GNU Screen](http://www.gnu.org/software/screen/) can be used like tip or cu.
The manual reads:
> Screen has built in some functionality of “cu” and “telnet”.
> If a tty (character special device) name (e.g. “/dev/ttya”) is specified
> as the first parameter, then the window is directly connected to
> this device.
So doing the following on my FreeBSD desktopscreen /dev/cuaa0
neatly connects to the first serial port with a usable terminal emulator.
Which came in handy today when one of my hosts panicked.