Microsoft has released a March 2013 Public Update, this seems to be a bit odd after releasing the February Cumulative Update. This hotfix fixes quite a few issues. Additionally, this update contains stability and performance improvements. A change in the package configuration was introduced after SharePoint Server 2013 was released. You must install this public update before you install later SharePoint updates.
Therefore, we need to install these updates otherwise, we will not be able to update in the future apparently. Furthermore this package includes the February 2013 Cumulative Updates.
The kb article about the Office Web Apps Server contains nothing about the issues that this hotfix will fix. However, as it turns out this update for Office Web Apps enables viewing and previewing for PDF files!
How to enable the viewing or previewing of PDF files is described in the blog post that Wictor Wilen wrote.
There is also another blog post of Wictor that’s very interesting: Patching a WAC farm with no downtime
Test the updates in a test environment before installing in production!!!