Microblogging is the name for things like Twitter. You "blog" only small texts like the famous 160 characters of Twitter. A tweet or toot would be called micropost or just "status update". On microblogs you usually don't have threads but replies to a post. These replies and the initial post effectively form a thread but all the replies are also separate posts by the user.
Keep in mind you are probably using server space by uploading multiple images at once, that others pay for. Is there a reason why you want to upload many images at once?