I have successfully updated my Drupal 7.24 site to use Media 2.x dev (2014-Mar-19) and Media Gallery (2014-Feb-26). The existing galleries are displayed perfectly.
The only issue I'm facing is that when I click on "Add Media" in a gallery, the "Upload images" tab is blank. All the other tabs ("Embed from URL", "Library", "My Files", "Library (MBP)", "My Files (MBP)") are visible and I can select existing pictures.
The blank tab is keeping me from uploading new images.
All modules required are installed (File Entity, Media Bulk Upload, Plupload). There are no errors in the log nor in the Apache access log.