Be sure to read the download page and the readme file (English only).
This Service Pack can be applied to AutoCAD 2015 and AutoCAD LT 2015 installed as a standalone application as well as AutoCAD 2015 and AutoCAD LT 2015 installed from the following suites or bundled products.
AutoCAD Civil 3D 2013 Service Pack 1 is now available for download! This Service Pack includes all previous hotfixes for AutoCAD Civil 3D 2013. It also includes the fixes included in AutoCAD 2013 Service Pack 1.1 and AutoCAD Map 3D 2013 Service Pack 1.
Thank you Autodesk! I have not installed it yet, but I'm looking forward to this fix -> "In drawings with a custom UCS, switching from the model tab to the layout tab will no longer reset model tab to isometric."
Update 2 for Civil 3D 2011 was released on June 30, 2011. You can find the download page here, along with the various language README files, which include a list of items addressed.
I was hoping this update fixed one particular bug, the one that causes the Prospector and Settings tab to go away after you run the ._PREVIEW command - but it does not. This is still an issue even after installing the update.
One thing to note: You must apply Update 1 before you can apply Update 2.
Lastly, to keep things interesting for us, after Update 2 is applied, the software will report that is is currently on "Version 3".