Now that the Windows XP, Office 2003 and Exchange 2010 SP2 support expiration date has come and gone, the world is still turning and we are not in a state of Armageddon! *
That said, focus now needs to be on Office 2010 as it is 6 months until support ends for Office 2010 SP1 on the 14th of October 2014. At that point all Office 2010 installations need to be on SP2. This is detailed in the notes column below, since support ends 12 months after the next service pack releases or at the end of the product's support lifecycle, whichever comes first.
The Microsoft support lifecycle site has the above details.
Office 2010 RTM support previously ended on the 10th of July 2012. If we look at the Office 2010 cumulative update for December 2013, specifically the Description of the Outlook 2010 hotfix package (Outlook-x-none.msp) we can see the platforms that the update supports. Please note that SP1 and SP2 are valid prerequisites for this update.
Outlook 2010 RTM is not listed as it was not a supported version at the time the update was released.
Is This Important?
In a single word – yes!
If you want to continue to receive security updates for your Office 2010 clients then you need to be at the correct level to get updates. Once Office 2010 SP1 has transitioned out of support then updates will not be available to that build of the client. There are lots of other great reasons to keep Outlook updated! There has been a lot of work to improve the client with recent updates for both on premises and O365 scenarios. You will only benefit from that work if you install the updates!
While we are discussing Outlook 2010 specifically here, the same holds true for all products covered with the Microsoft support lifecycle. Please sign up for the Microsoft Support Lifecycle Quarterly Update Newsletter to stay abreast of supportability dates and ensure you get the support you deserve!
* – Armageddon was the first DVD that I bought back in 1999, and can remember having to shell out for not just the DVD player but also the hardware decoder card since a Pentium 200 did not really have the juice to render the video!