I help quite a few people out with their blogs and have run into a consistent bit of confusion around uploading images in version 2.0.
In the file upload section you upload a file by first clicking on the "Upload" tab, select an image and then click on the "Upload" button. People seem to get somewhat confused as both the tab and the button are labeled "Upload". People tend to click on the Upload tab instead of the Upload button which then refreshes the screen removing their selected file from the File box.
The tab should be re-labeled "Add File". This would eliminate any confusion.