This will be welcome news for those who regularly save a bunch of tweets.
According to a new finding posted by reverse engineering expert Jane Manchun Wong, Twitter is working on a new folders option within the Bookmarks tab, which would enable users to save tweets into a range of defined categories - or 'Collections', as Twitter is currently calling them.
As you can see here, the new process would enable you to create category folders within your Bookmarks tab. You would then be able to choose which folder/collection you want to save a tweet to when you go to bookmark it in-stream (last screenshot above).