After all of these continual reboots on the Xamarin.iOS SDK update, I noticed this error on startup in Visual Studio 2013. Not sure if anything is related or not, but I wanted to post it. It looks like an error in the startup of the X.i toolbar in VS.
Mono.IOS.VisualStudio.MonoTouchPackage Warning: 0 : Initializing Mono.IOS.VisualStudio.MonoTouchPackage Mono.VisualStudio.Extension.TastyPackage Error: 0 : Failed to show control 'Standard' in toolbar 'Build.SolutionPlatforms' System.Runtime.InteropServices.COMException (0x80004005): Unspecified error (Exception from HRESULT: 0x80004005 (E_FAIL)) at EnvDTE.Command.get_IsAvailable() at Mono.VisualStudio.Extension.TastyPackage.DoToggleToolbarControlVisibility(String aToolBarName, String aControlName, String aControlDisplayName, String aAfterControlName, String aAfterControlDisplayName, Boolean visible) at Mono.VisualStudio.Extension.TastyPackage.ToggleToolbarControlVisibility(String aToolBarName, String aControlName, String aControlDisplayName, String aAfterControlName, String aAfterControlDisplayName, Boolean visible)
[2013-12-04 14:57:59.7] INFO:Found Xcode, version 5.0.2 (3335.32). [2013-12-04 14:57:59.9] INFO:Found Xamarin.iOS, version 7.0.4.209. Mono.Android.VisualStudio.MonoAndroidPackage Warning: 0 : Build server returned an Warning. Mono.IOS.VisualStudio.MonoTouchPackage Warning: 0 : Build server returned an Warning. Mono.Android.VisualStudio.MonoAndroidPackage Warning: 0 : Negotiating server information for pairing process. Mono.IOS.VisualStudio.MonoTouchPackage Warning: 0 : Negotiating server information for pairing process.