• Mac OS X 10.5.5 Combo Update
• Mac OS X 10.5.5 Update (Delta)
• Mac OS X Server 10.5.5
• Mac OS X Server Combo 10.5.5

They also have a download page with WebObjects Update 5.4.3 for Mac OS X 10.5.
I applied the Combo updater on an AL iMac and have not seen any issues so far - some early mails on 10.5.5 have been postive including a reader saying Fallout 2 and Diablo II are fixed (previously had problems in leopard - see earlier page here on Graphics issues with earlier 10.5.x versions.)

• Security Update 2008-006 Client (Intel)
• Security Update 2008-006 Client (PPC)
• Security Update 2008-006 Server (PPC)
• Security Update 2008-006 Server (Universal)

Details on changes/fixes are in this Apple doc.

I have a Magma 4-slot PCI expansion chassis (PCI4DRQ.) This has a PCI host card and has run well with 3 Universal Audio UAD-1 cards in it an another UAD-1 and a MOTU PCI(X)-424 in a early 2005 Dual 2GHz G5 tower (not PCI-express model - PCI slots only) It's the only time the 2.0Ghz spec was the "low end" model. It didn't have the AMD chipset and did not feature PCI-X. It was much more stable with many Pro Audio PCI cards. Would not accept older 5V cards of course. It has always worked extremely well...

The time has finally come for a Mac Pro (current 5400 Xeon series - standard 2.8Ghz model) and the chassis has been deployed with a new PCIe host card from Magma.
However, any time I would play ANY audio, even if it didn't directly involve a UAD plug in or the MOTU Audio Interface, a kernel panic would occur instantly. The MOTU-424 PCI also does not work in the chassis either. At all.
As it turns out after many hours of diagnosis, and confirmed by knowledgeable staff at Magma:

If you have an older 4-Slot chassis with a "Dec" branded chipset, you can only put ONE UAD-1 card in the chassis when using a Mac Pro. There are known compatibility issues with these older units and all Mac Pro's.

I figured it has to be due to the way the PCI signals are handled by the UAD-1's and the chipset in the Mac, even though there is a PCIe host card "in-between." This was pretty much confirmed by Magma. "Dec" was a brand manufactured by Intel, but discontinued some years ago.

Their solution is the change the board in the chassis for a newer revision, which shouldn't too much trouble, costs notwithstanding.

Hope this helps someone else who may be thinking of using a Magma chassis to extend the life of some PCI cards. Make sure to get a newer Magma 4-slot chassis!
Kind regards, James"

While on the subject, the 2008 Mac pro page here had some past notes on issues with some PCIe controller cards in Slot 2 after the last (2008) Mac Pro firmware update - moving cards to another slot (i.e. slot 4 or slot 3) worked to get them recognized again. (James later wrote his controller card for the chassis was in slot 4.)

• Sonnet G4 1.4GHz in (Quicksilver 733MHz) G4/AGP tower
  (includes notes on other OEM cpu swaps, OEM QS heatsink swap on sonnet upgrade)
  
  (Full reviews of G4 and G3 upgrades compared to stock CPUs, including real world apps/game tests, install info, etc. are linked at the G4 upgrade reviews and G3 upgrade reviews pages. Intel-CPU chip swaps (i.e socketed Mac Mini) and OC/CPU module articles are on the Systems page.)

If you've upgraded the CPU on your Mac, send a review with your experience (performance/stability/installation, etc.), Mac Model/Upgrade brand info and overall rating (1= worst to 10=best). If you can, please run some tests with the original CPU vs the upgrade (for example time some tests with your favorite app, game, etc. - see full reviews here for example tests with common apps/games/benchmarks.)

• Survey: Plans to buy a Mac hit an all-time high (Fortune)
• Review: iPhone 2.1 Software (iphoneblog)
• Users Divided Over Efficiency of iPhone OS 2.1
• Studios Bid On Liberating Digital Media 'Ecosystem' (PCworld)
• Should Apple join new video ecosystem? (cnet)
• Hard Choices: iPhone, iPod Nano and Gates-Seinfeld (technewsworld)
• Dashball for iPhone Debuts, Combining Breakout and Labrynth Gameplay
• Best Buy nabs Napster for $121 million (cnet)
• VLC Media Player 0.9.2
• NeoOffice 2.2.5
• EarthDesk 4.4.1
• MacPilot 3.1.3
• Apple blocks competitive products from iPhone App Store--surprised? (cnet)
• Chrome's Corporate Review (forbes)
• Could There Be More To Google, Android, Chrome, & Gears Than Meets The Eye? (informationweek)
• Spore And The Great DRM Backlash (wash. post)
• Home-Brewed Biodiesel Goes Prime-Time