Red means the piece of equipment is not supported (as hot or warm-swappable, anyway), and will never be. Blue means it may possibly work in the future, but does not now. Green means it is fully functional, and yellow means there's no reason why it oughtn't work, but I haven't gotten a confirmation. If you can confirm any of these, please let me know.
|Brand||Model||Bay 1||Bay 2||Dock|
|IBM||A31p||Ultrabay 2000 (1)||Ultrabay Plus||None|
(1) an Ultrabay battery will still be brought into ACPI 'hot', however.