OK, following patch fixes this: (just add the line with new ID to the array initialization). After rebuild/install, Calibre recognizes my Kindle Fire HD 8.9
Code:
*** calibre/src/calibre/devices/mtp/unix/devices.c.old 2012-12-27 15:39:46.218207350 -0800
--- calibre/src/calibre/devices/mtp/unix/devices.c 2012-12-27 15:36:17.480203715 -0800
***************
*** 13,18 ****
--- 13,19 ----
// Amazon Kindle Fire HD
, { "Amazon", 0x1949, "Fire HD", 0x0007, DEVICE_FLAGS_ANDROID_BUGS}
+ , { "Amazon", 0x1949, "Fire HD", 0x0008, DEVICE_FLAGS_ANDROID_BUGS}
, { "Amazon", 0x1949, "Fire HD", 0x000a, DEVICE_FLAGS_ANDROID_BUGS}
// Nexus 10