I decided myself to make a scan of zip arhive of wordpress 3.6 to know what's happen. And bellow are the results of archive. I mention that my PC is clean no viruses and malware.
Perhaps that's why many have confronted with problems at update and obviously me that I am confronted with the problem of adding plugins and themes inside the administration interface.
Problems with new WordPress I made an online Scan of archive and 2 malware inside the zip archive.
First two sites show us that WordPress 3.6 is infected with two malware