With the introduction of patch 1.4, it's possible to stack 'big' items like kegs and so forth. But it does not work to stack fishing bobbers (and probably other types). This would be great for when I go for a whole day of fishing, where one can go through 2-3 of these. Would be much preferred to have these only take up one inventory space instead of 2-3. Actually even more so post-1.4, since it's possible to get iridium fish in addition to typically only gold once you reach a high fishing level. Which of course means more problems to fit everything in the 36 inventory spaces, given that at least 10 are taken up for tools and stone, wood etc.