The lt_hotswap kernel module enables hot-swapping for disk drives with full DMA support under Linux. It should work on any laptop with hot-swappable bays and ACPI support.
Latest version: http://churchofjim.org/sources/lt_hotswap-0.2.0.tar.gz
Development and discursion of lt_hotswap is currently being held in Linux-ThinkPad Mailinglist.
Users report success with T22 and T40 on mailing list, although many other models should also work.