When I try to publish be I get the following error:

Error 1 The command "xcopy E:\Blogengine Source\GHC\Source\BlogEngine\..\lib\optimization\System.Web.Optimization.dll E:\Blogengine Source\GHC\Source\BlogEngine\BlogEngine.NET\Bin\ /F /R /Y /I
xcopy E:\Blogengine Source\GHC\Source\BlogEngine\..\lib\razor\*.dll E:\Blogengine Source\GHC\Source\BlogEngine\BlogEngine.NET\Bin\ /F /R /Y /I
xcopy E:\Blogengine Source\GHC\Source\BlogEngine\..\lib\watin\Interop.SHDocVw.dll E:\Blogengine Source\GHC\Source\BlogEngine\BlogEngine.Tests\Bin\Debug\ /F /R /Y /I
xcopy E:\Blogengine Source\GHC\Source\BlogEngine\..\lib\watin\BlogEngine.Tests.dll.config E:\Blogengine Source\GHC\Source\BlogEngine\BlogEngine.Tests\Bin\Debug\ /F /R /Y /I" exited with code 4. BlogEngine.Core

I believe I am using the c68c69a968b0 release.....Not sure though. 

It might be because of the space in your folder name (BlogEngine Source), the Post Build command may need to have its arguments wrapped in double quotation marks.
http://stackoverflow.com/questions/5626557/what-is-going-wrong-when-visual-studio-tells-me-xcopy-exited-with-code-4

I haven't looked at it, but you might need to edit the Post Build command in Visual Studio (in the BlogEngine.Core project properties) and wrap some of the arguments in double quotation marks.

Some other results....
https://www.google.com/search?q=exited+with+code+4 

Good stuff BenAmada, I put the double quotes in the following xcopy arg:

xcopy "$(SolutionDir)..\lib\watin\BlogEngine.Tests.dll.config" "$(SolutionDir)BlogEngine.Tests\Bin\Debug\" /F /R /Y /I

and we're green.

Thanks.

BTW, do you have any tips on deploying a custom version of be from vs2010? Any tips or gotchas would be helpful.

Again, thanks.

I am getting the same issue, I tried to put double quotes but it didn't change a thing

My post Build Command

xcopy "$(SolutionDir)..\lib\optimization\System.Web.Optimization.dll" "$(SolutionDir)BlogEngine.NET\Bin\" /F /R /Y /I
xcopy "$(SolutionDir)..\lib\razor\*.dll" "$(SolutionDir)BlogEngine.NET\Bin\" /F /R /Y /I
xcopy "$(SolutionDir)..\lib\watin\Interop.SHDocVw.dll" "$(SolutionDir)BlogEngine.Tests\Bin\Debug\" /F /R /Y /I
xcopy "$(SolutionDir)..\lib\watin\BlogEngine.Tests.dll.config" "$(SolutionDir)BlogEngine.Tests\Bin\Debug\" /F /R /Y /I

The error

Error	18	The command "xcopy "E:\Mydata\Visual Studio 2010\Projects\BlogEngine2012\..\lib\optimization\System.Web.Optimization.dll" "E:\Mydata\Visual Studio 2010\Projects\BlogEngine2012\BlogEngine.NET\Bin\" /F /R /Y /I
xcopy "E:\Mydata\Visual Studio 2010\Projects\BlogEngine2012\..\lib\razor\*.dll" "E:\Mydata\Visual Studio 2010\Projects\BlogEngine2012\BlogEngine.NET\Bin\" /F /R /Y /I
xcopy "E:\Mydata\Visual Studio 2010\Projects\BlogEngine2012\..\lib\watin\Interop.SHDocVw.dll" "E:\Mydata\Visual Studio 2010\Projects\BlogEngine2012\BlogEngine.Tests\Bin\Debug\" /F /R /Y /I
xcopy "E:\Mydata\Visual Studio 2010\Projects\BlogEngine2012\..\lib\watin\BlogEngine.Tests.dll.config" "E:\Mydata\Visual Studio 2010\Projects\BlogEngine2012\BlogEngine.Tests\Bin\Debug\" /F /R /Y /I" exited with code 4.	BlogEngine.Core

Do you actually have files in the paths? If you run it from command line - does it work? The command itself looks good to me and I checked it with project moved to "folder with spaces", worked fine.

I mean run from cmd command:

xcopy "E:\Mydata\Visual Studio 2010\Projects\BlogEngine2012\..\lib\optimization\System.Web.Optimization.dll" "E:\Mydata\Visual Studio 2010\Projects\BlogEngine2012\BlogEngine.NET\Bin\" /F /R /Y /I

Spot on rtur, thanks for your help