I'm a little late to this party, but wanted to ask... When I am using a web based email program like Netzero or my companies Outlook client, I also cannot attach files... The "choose file" or "select file" button that would normally bring up a file browser is greyed out. Am I to understand this is also a result of "sand boxing"? I am on a jailbroke iPad 3... Is there any work-around?
Any feedback appreciated, and feel free to bump me to the hack section if that seems appropriate.