Windows OS

Lots of products work out of the box without change, while others will need updates, and some will probably never run on Server 2008.

To stay up to date on what works and what doesn't, check out KB 948680.

Current list of incompatible products:
BizTalk 2004 and earlier versions of BizTalk
Commerce Server 2002 and earlier versions of Commerce Server
Compute Cluster Server 2003
Dynamics CRM 3.0 and earlier versions of Microsoft Dynamics CRM
Exchange Server 2003
Host Integration Server 2004 and earlier versions of Host Integration Server
Internet Security and Acceleration Server 2006 and earlier versions of ISA Server
Office Communications Server 2007
Speech Server 2004 R2
SQL Server 2000 and earlier versions of SQL Server
System Center Reporting Manager 2006
Systems Management Server 2003

I'm doing a lot with Server 2008 lately so expect many Server 2008-centric posts for a while.

This website provides information on SPS and Windows 2008.

Their description describes the site better than I can, which is:
This page provides IT pros with resources to help deploy Windows SharePoint Services 3.0 and Microsoft Office SharePoint Server 2007 to Windows Server 2008.

As of Windows SharePoint Services 3.0 with SP1, you can install Windows SharePoint Services 3.0 and Office SharePoint Server 2007 on Windows Server 2008. You cannot install Windows SharePoint Services 3.0 or Office SharePoint Server 2007 without service packs on Windows Server 2008.

Windows SBS 2000/2003 enforce a limitation that permits only one Windows SBS domain controller in the domain. This software update extends the allowable grace period for the supported scenarios from 7 days to 21 days.

I suspect "Cougar", aka SBS 2008, will have the same 21 day limitation.

Update Rollup 6 is out for Exchange 2007 RTM, for those who have no upgraded to SP1 yet. It fixes over 20 bugs, and includes all the fixes from Rollup Packs 1 thru 5.

A good KB article to bookmark to stay on top of these releases is KB 937052. When an update rollup for SP1 comes out, it will be listed there.

If you want your Windows 2003 VHDs to migrate back and forth between Virtual PC, Virtual Server, and Hyper-V as easy as possible, make sure they are running the ACPI multi-cpu HAL.

Hyper-V installs this HAL into any VHD image you put the Integration Services (IS) on. IS is vastly different than Virtual PC addition – think of them as native synthetic drivers and not emulations. You have to uninstall Virtual PC additions before you can install the Integration Services.

Breakdown by OS (so far that I have discovered):

Windows 2000 – do the same as 2003, but it seems more resilient to going back and forth due to a lack of native Integration Services (so far).

Windows XP – do the same as 2003.

Windows 2008 – it has Hyper-V support natively.

Windows Vista SP1 – I think you can hijack it and get the Windows 2008 IS pieces to work – haven’t tried yet.

For Linux, go to Microsoft's Connect site and download the Integration Services for Linux – so far, only Novell/Suse is supported but I am sure if you roll your own kernel, you can hack the patches in yourself (haven’t tried yet).

Some of this information I originally stumbled upon here.