Some days we look at the web and see new and interesting things. Some days you just see stuff that breaks things. Today, Flash 10 is one of those. If you haven't heard the news, Flash 10 breaks a lot of web uploaders - ours included. Of course we're not the only one who has been impacted by this issue and it has been an issue during the beta. Solutions are coming out to resolve the issue and to Adobe's credit it has been documented. The issue in the short term is that Joomla!'s upload functionality isn't working if you're using Flash 10, so if this is functionality that you're really tied to try to avoid upgrading to Flash 10. Alternatively you can just disable the Flash uploader completely in Site > Global Configuration > System > Enable Flash Uploader and setting this to 'No'. At least for the current version of Joomla! (1.5.7) and for the next version that we're working on (1.5.8) we're not going to be in a position to update the library to fix the problem for Flash 10. Once fixes have been made available and tested we'll shift it into the next version of Joomla!.