Holding the 'option/alt' key and then pressing the left, up, right, or down arrow does not work properly. When in a text field, like this field "Description", and entering/editing text, if the option/alt + left or right arrow key is pressed the action experienced is now the same as option/alt + cmd + left or right arrow (switch tab) instead of jumping left or right between the text entered in the field. When option/alt + up or down arrow keys are pressed something seems to happen to the tab, it's moved to the front or end of the tab list, instead of moving the cursor to the beginning or end of the text in the text field. Interestingly the keyboard combination works properly in Gmail while composing a message.
While editing a Post on wordpress.com the keyboard combination works properly. the keyboard combination does not work properly while adding a status update on facebook.com and hootsuite.com or a search on google.com and yahoo.com.
Testing further it appears that the extension "Smooth Gestures - Version: 0.13.3" was causing the issue.