On the publishing site I've created a simple page with a Page Content. I've added a web part there and then I'm trying to add a Reusable Content. However it turns into
a like here
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This bug has been fixed in the June Cumulative Update: http://sergeluca.wordpress.com/2011/09/06/reeusable-content-bug-fixed-in-the-june-cu/
I also verified this myself. I can now add reusable content and web parts within the same publishing field.
Dave has a point:
The workaround is to create custom layout based on the custom content type which itself is based on the publishing page content type. Also you have to add a new column of type "Full HTML content with formatting and constraints for publishing". You can add several depending on your needs. Then you can edit the custom layout in SP designer and add already defined custom content fields there