OK, I reinstalled from the daily debian-testing-amd64-netinst.iso dated
13 December 2008 on my MacBook Pro 4,1 (Penryn), dual-booting with Mac
OS X Leopard, using partitions /dev/sda3 and /dev/sda4 for root and
swap, respectively. As before, installation went without any problem,
with again the installer correctly detecting EFI/GPT and automatically
installing Grub-2 (grub-pc): I opted for installing it to the MBR.
Upon reboot, the rEFIt boot manager showed both Mac OS X and GNU/Linux
icons, but selecting the latter gave a "boot media not found" message
--- a known problem, since the MBR partition table must first be
synchronized with GPT. On my wish-list is to have the installer do this
(e.g. with the gptsync utility). In the event, I rebooted and used the
Partition tool in the rEFIt menu, then rebooted once more, chose the
GNU/Linux icon and lo! the Grub menu appeared and few seconds later the
familiar Debian login screen.
So, it appears that my earlier Grub problem has been solved, for which I
thank the developers.
"Behavioral axioms are right, but agents make mistakes."
Attributed to L.J. Savage