Several people who would benefit by installing the cumulative update told me they were unsure if they should install it “because it’s a hotfix and hotfixes do not have support” or the same level of testing that service packs have.
Yes, you should install it.
The cumulative update underwent the same type of testing normally given to service packs and is fully supported, like every service pack is. It was released ahead of Office SP2 because the Outlook team felt users would benefit greatly from the improvements in performance and reliability now, not weeks from now. The best path for release outside of an SP is as a hotfix, which has led some to be leery of installing it ahead of the "official" SP release.
Bottom line: Admins (or users) should treat this download as they would an SP, not a hotfix. If your policy is to wait to install SPs, then wait; if the policy is to install SPs, go ahead and enjoy the speed.
For more information of the fixes contained in this update,
see Outlook 2007 Cumulative Update White Paper:
http://support.microsoft.com/?kbid=968009
Outlook 2007 update download:
http://support.microsoft.com/?kbid=961752
Microsoft is rolling out a service called
Fixit. When the solution to a problem can be
fixed by an automated method (usually involving
editing the registry), Microsoft will include the
FixIt wizard in the article along with the manual
steps. The number of FixIt enabled articles is
expected to grow and cover all applications, but
at this time most of the FixIt's are for Windows
problems with a very limited number of FixIt
enabled articles for Outlook and Exchange server.
The Fixit wizard is currently in English only but
many of the fixes are supported on Office and
Windows in other languages.
When a KB offers a prepared fix for the issue
described in the article, it will have a Fixit
button, as seen in this KB article:
http://support.microsoft.com/kb/951291/
To browse the FixIt solution center, visit http://support.microsoft.com/fixit
Once again Microsoft is planning to change the
web address of the Knowledgebase - moving
developer content to MSDN and IT content to
TechNet. All
http://support.microsoft.com sites
that provide support for IT Professionals and
Developers will be directed to TechNet and MSDN.
This change was supposed to go into effect this
week but all of the articles I checked are all
still on support.microsoft.com.
When the move is complete, the new URL format
will be:
http://technet.microsoft.com/kb/<article#>
http://msdn.microsoft.com/kb/<article#>
Microsoft has promised to redirect existing links
but based on my experience with previous URL
changes at Microsoft, the redirects won't last
beyond a year or so.
You'll be able to scope the articles in search
engines by using either
site:technet.microsoft.com/kb or
site:msdn.microsoft.com/kb, depending on the type
of content you are looking for.
Currently, hotfixes and security updates will
remain at support.microsoft.com but they are
expected to eventually move to MSDN or TechNet,
based on the type of hotfix.
A message that contains one
byte Kana stays in the Directory Lookup queue in
Exchange Server 2003 when the message is sent by
using OWA
http://support.microsoft.com/?kbid=963683
An MDM device returns a "partial success" message
because Exchange 2003 does not recognize the
device
http://support.microsoft.com/?kbid=967046
Clicking 'Connect To This Discussion board' in
SharePoint alert email gives error (0x800401F3)
http://support.microsoft.com/?kbid=968484
Event ID 459 may be logged after you perform a
backup of an Exchange Server store in Exchange
Server 2003 by using the NTBACKUP tool
http://support.microsoft.com/?kbid=946799
Event ID 9582 message is logged in the
Application log on an Exchange Server 2003 server
http://support.microsoft.com/?kbid=960144
The search operation is aborted in Exchange
Server 2003 when an Exchange store includes a
corrupted HTML message
http://support.microsoft.com/?kbid=958179
Outlook 2007: PST and OST
files may be up to 20% larger after the February
24, 2009 Cumulative Update
http://support.microsoft.com/?kbid=968413
Outlook:URL Protocol is Not Functional in Outlook
2007
http://support.microsoft.com/?kbid=968416
The contact linking information is missing in a
meeting request that is sent from Outlook 2007
http://support.microsoft.com/?kbid=967579
Outlook 2007: New information in the InfoBar for
messages in the Junk E-Mail folder
http://support.microsoft.com/?kbid=968383