I’m not certain this tip will work on all laptops, but it does on my Dell Inspiron 3500.
Under Win98 or NT, if you want to change from the modular CD-ROM drive to Zip or floppy etc, you have no choice but to shut down, swap drives (or battery) and reboot. [Editor’s note: My Inspiron 3500 came with a SwapBay util in the control panel, but it’s slow and unreliable]. Even then, hot-swapping these modular drives under Win98 or WinNT will often crash the system entirely, or freeze the shutdown process.
Under BeOS, however, you can simply swap the device, run DriveSetup, and pull down Rescan | IDE. The new drive appears in the Mount menu, ready to mount. Very convenient when I need the uptime provided by two batteries but need to quickly get a file off of Zip disk.
If you prefer to use the command line rather than DriveSetup, these commands will achieve the same effect:

 rescan mountvolume -all 

mountvolume --help will tell you that the flag -r will rescan automatically, but I found it unreliable. You can make these into a little script by putting the ‚magic cookie‘ (#!/bin/sh) at the top, and running chmod +x on the file. Once you’ve got a working script, link to it from the Be menu — whenever you swap a drive, you can just run the script to mount the new volume on the desktop.