When I got my memory stick, I found it very useful to let it have its own personal entry in my /dev. Since my Gentoo box is running a 2.6 kernel with udev, it was time to investigate udev rule writing. I found this site to be particulary usefull: http://www.reactivated.net/udevrules.php. 
The next line in /etc/udev/rules.d/10-local.rules, did the trick:

BUS="scsi", SYSFS{model}="UsbFlashDisk", KERNEL="sd?1", NAME="%k", SYMLINK="usbstick"

It creates a symlink, called 'usbstick', to my usb scsi device which got added by hotplug.