One benefit for businesses using Office 365 is the ease in which their systems can be updated with the latest patches. This benefit can translate into substantial time and revenue savings depending on the number of File, SharePoint, Lync and Exchange servers being managed in the Office 365 cloud.
In large enterprises, server updates would go through a comprehensive change management cycle, which would begin with hardware testing and application testing. Once the testing is complete, products such as Microsoft WSUS or Microsoft SCCM would be used to deploy the patches to pilot servers, then critical servers and finally a scheduled deployment would be applied to the rest of the servers.
With Office 365, Microsoft relieves businesses of this onerous administrative task, although businesses will still have to retain an update change management cycle for clients connecting to Office 365 in order to maintain their client security and in some cases achieve better connectivity. Last month, Microsoft released a client-side update described in article KB2553248 that contained stability and performance improvements and fixed issues with recurring meetings and online archiving between Exchange Online and Outlook. This update is essential for Office 365 users who connect to Exchange Online with the Outlook client and so their computer would need to be patched through their regular update methods.
For large businesses, this patch would be deployed by WSUS or SCCM and for smaller businesses via the Windows Update Service. The important point to remember is that as long as any on-premises client desktops and laptops are being used, these clients will still need regular patching. Microsoft can only apply the server and web app update procedures to the systems you have in the Office 365 cloud. See Microsoft's May 2012 Security Bulletin for the latest security patches for your systems or visit Windows Update and click on Check for Updates to see whether you have the latest patches.