Update
SuperDrive Firmware Update 2.1
The SuperDrive Update (12MB) improves readability of certain CD media.System Requirements:Mac OS X 10.4.4 or laterMacBook Pro Core Duo (15 -inch 1.83GHz, 2.0GHz, or 2.16GHz)MacBook Pro Core 2 Duo (15 -inch 2.16GHz or 2.33GHz)MacBook Core Duo (13 -inch 1.83GHz or 2.0GHz)MacBook Core 2 Duo (13 -inch 1.83GHz or 2.0GHz)
Battery Update 1.2
Apple has released Battery Update 1.2 for the following products (basically all the MacBook and MacBook Pro models as at May 2007):
  • MacBook
  • MacBook (Late 2006)
  • MacBook Pro (15-inch)
  • MacBook Pro (15-inch Glossy)
  • MacBook Pro (15-inch Core 2 Duo)
  • MacBook Pro (17-inch)
  • MacBook Pro (17-inch Core 2 Duo)
Battery Update 1.2 may be downloaded here (244kB):
http://www.apple.com/support/downloads/batteryupdate12.html

For more information, please see here:
http://www.apple.com/au/support/macbook_macbookpro/batteryupdate/
Apple announces EFI Firmware Updates for Intel Macs
This EFI Firmware Update fixes several Boot Camp, start up, and wake-from-sleep issues on Mac Pro, iMac, MacBook Pro, MacBook and Mac mini computers:

Mac Pro EFI Firmware Update 1.1 (1.6MB)
http://www.apple.com/support/downloads/macproefifirmwareupdate11.html

iMac EFI Firmware Update 1.1 (6.1MB)
http://www.apple.com/support/downloads/imacefifirmwareupdate11.html

MacBook Pro EFI Firmware Update 1.2 (2.7MB)
http://www.apple.com/support/downloads/macbookproefifirmwareupdate12.html

MacBook EFI Firmware Update 1.0 (1.6MB)
http://www.apple.com/support/downloads/macbookefifirmwareupdate10.html

Mac mini EFI Firmware Update 1.1 (1.6MB)
http://www.apple.com/support/downloads/macminiefifirmwareupdate11.html

A Firmware Restoration CD 1.2 is also available (20.5MB)
http://www.apple.com/support/downloads/firmwarerestorationcd12.html
MacBook Firmware Update
MacBook SMC Firmware Update 1.1 (<1MB)
http://www.apple.com/support/downloads/macbooksmcfirmwareupdate11.html

The SMC Update improves the MacBook's internal monitoring system and addresses issues with unexpected shutdowns. This update is recommended for all MacBook systems, including those that received warranty repair.

Note:
"If your MacBook is running Mac OS X 10.4.6, you won't be able to install the SMC Update until you update to Mac OS X 10.4.8. MacBooks running Mac OS X 10.4.7 will be able to download and install the SMC Update, so it is not essential that you update your system software, although Apple always recommends updating to the latest version of the system software.

After this update has completed successfully, your SMC Version will be: 1.4f12."
Mac Pro Firmware Updates, Firmware Restoration CD v1.1
Mac Pro (mid 2006) EFI Firmware Update 1.0
This EFI Firmware Update fixes several Boot Camp and start up issues on Mac Pro computers:
http://www.apple.com/support/downloads/macpromid2006efifirmwareupdate10.html

Mac Pro SMC Firmware Update
The SMC Firmware Update adjusts fan behavior in the Mac Pro:
http://www.apple.com/support/downloads/macprosmcfirmwareupdate.html

Firmware Restoration CD v1.1
This update is used to restore the firmware of an Intel-based iMac (early & mid 2006), Mac mini (early 2006), MacBook Pro (early 2006), Mac Book (early 2006), or Mac Pro (mid 2006) to original factory condition:
http://www.apple.com/support/downloads/firmwarerestorationcd11.html

It can only be used to restore the Firmware after an interrupted or failed update.
MacBook SMC Firmware Update
http://www.apple.com/support/downloads/macbooksmcfirmwareupdate.html
The SMC Firmware Update adjusts fan behavior in the MacBook.
SMC Firmware Updates for 17-inch MacBook Pro
SMC (System Management Control) Firmware Updates for 17 inch MacBook Pro. Address fan behaviour.

MacBook Pro 17 inch SMC Firmware Update (<1MB) updates MacBook Pro 17 inch only.
SMC Firmware Updates
SMC (System Management Control) Firmware Updates. Address boot issues.

iMac (early 2006) SMC Firmware Update (<1MB) updates iMac computers with Intel processors only.
MacBook Pro SMC Firmware Update (<1MB) updates MacBook Pro computers with Intel processors only.
Mac mini (early 2006) SMC Firmwmare Update (<1MB) updates Mac mini computers with Intel processors only.

About the SMC Firmware Update 1.0.
Intel Mac EFI Firmware Updates
Apple released three firmware updates which deliver EFI with BIOS support for the Intel Macs. These do not appear automatically via the Mac OS X Software Update mechanism, so you must download and install them manually.

iMac (Intel) Firmware Update 1.0.1 (2.8MB) updates iMac computers with Intel processors only.
MacBook Pro (Intel) Firmware Update 1.0.1 (2.8MB) updates MacBook Pro computers with Intel processors only.
Mac mini (Intel) Firmware Update 1.0.1 (2.8MB) updates Mac mini computers with Intel processors only.
Firmware Restoration CD v1.0 (8.7MB) can restore the firmware of an Intel-based iMac (early 2006), Mac mini (early 2006), or MacBook Pro (early 2006) to original factory condition. It can only be used to restore the Firmware after an interrupted or failed update.

The following Knowledge Base article provides more information on the firmware updates:
http://docs.info.apple.com/article.html?artnum=303364