Another site is also affected by this problem.
The vast majority of errorrs is related to seo ultimate plugin
Here is an exaple of debug log file
2013-07-02 20:22:18 000000 — PHP [E_STRICT] 2048 : Non-static method suio::is_dir() should not be called statically, assuming $this from incompatible context in /wp-content/plugins/seo-ultimate/plugin/class.seo-ultimate.php at line 472
2013-07-02 20:22:18 000000 — PHP [E_STRICT] 2048 : Non-static method suio::tslash() should not be called statically, assuming $this from incompatible context in /wp-content/plugins/seo-ultimate/includes/jlfunctions/io.php at line 33
2013-07-02 20:22:18 000000 — PHP [E_STRICT] 2048 : Non-static method suio::untslash() should not be called statically, assuming $this from incompatible context in /wp-content/plugins/seo-ultimate/includes/jlfunctions/io.php at line 44
2013-07-02 20:22:18 000000 — PHP [E_STRICT] 2048 : Non-static method suio::is_file() should not be called statically, assuming $this from incompatible context in /wp-content/plugins/seo-ultimate/plugin/class.seo-ultimate.php at line 483
2013-07-02 20:22:18 000000 — PHP [E_STRICT] 2048 : Non-static method sustr::endswith() should not be called statically, assuming $this from incompatible context in /wp-content/plugins/seo-ultimate/includes/jlfunctions/io.php at line 19