Now facebook user will be able to upload big image as it wasn't available earlier & it was very irritating. Facebook is going to increase the maximum size limit for uploading photos from 720 pixels to 2048 pixels (approximately 8 times more). This function is added today & soon it will be available to all facebook users.
Another new addition is made for photo viewer. which now, will be darker & with new navigational buton for "Next" & "Previous" Images. Hopefully they will also change the gallery look or may be also adding some more features too. Possibly you will get notification at your facebook anytime.