FortiOS 5.2.9 is out
http://docs.fortinet.com/uploaded/files/3285/fortios-v5.2.9-release-notes.pdf
The list of the resolved issues is important IMHO, just some tips:
297421 HTTPs traffic is blocked after AV/IPS database update from FortiGuard.
306929 Fortigate memory logging is automatically enabled after reboot.
382828 When trying to access internal server through SSL VPN in web mode, the login page is not
371264 Modify user ran into lock when trying to change user's password during sslvpn connection.
376599 Keep IPSec traffic on the hardware during rekeying causes kernel panic.