Let me preface this by saying I know my drive/partition layout isn't optimal; right now I'm testing Chameleon to ensure it works for all of my needs before I give grub the heave-ho.
Simply put, my Linux partition is not displayed by Chameleon, in either the text or GUI modes (not that there should be a difference). My drive layout is as follows:
Drive 1: 4GB SSD, MBR partition map
Bootsector: Grub
hd(0,1): Ubuntu 9.04 (using grub)
hd(0,2): BIOS (another I'd like to hide)
Drive 2: 64GB SSD, MBR partition map
Bootsector: Chameleon 2.0rc1
hd(1,1): Leopard
hd(1,2): WinXP (using NTLDR)
hd(1,3): Win7 (using BCD)
hd(1,4): Data (+1 vote for hiding partitions :) )
Drive 3: 16GB SD Card, MBR partition map
hd(2,1): SD (yet another I'd like to hide)
Grub comes up first, as it fairly seamlessly boots into Linux, Mac OS X, Windows XP, Windows 7, saves the last boot selection, etc. (t's just ugly, so I'd rather use Chameleon). From there, I chainload over to Leopard, and use map to swap primary and slave drives; otherwise I tend to get "waiting for root device" problems when booting into OS X. Chameleon loads and works fine; I can still boot back to Windows XP. However, I can't get it to see my Linux partition.
Ultimately, Chameleon will replace grub on the primary drive and these various id's will change, but I doubt that will affect my core problem of Linux not showing up - and I don't want to commit to that until I know it will work.