In a new post on the Facebook blog, Facebook have announced they will be rolling out a new updated photo size for ‘better viewing’.
Old photo size (left) compared to the new size. (Note that actual photos are larger; this shows scale only.)
There is a caveat for external applications that upload photos to Facebook (i.e. Windows Live Photo Grallery, iPhoto etc).
All uploads on Facebook.com will support the new photo size, but uploads made from some external applications may continue to use the previous size.
This will likely be remedied with an update to the application or plugin.
Ultimately this is a good thing, the limited photo size has been a contentious issue for many, particularly photographers eager to show off their work. Sites like Flickr allow photos to be uploaded and viewed in a variety of sizes including full resolution.