The problem being that attach looks to use nothing but standard Apple functionality, so it's not like you could detect any malware etc.
For this particular attack, you could turn off the 'find my iPad' setting, they it could not be remotely locked, but that just opens up another can of worms if you did want to lock / locate it.
It's not clear yet whether there's been a hack on Apple's side, or whether someone is just trying username / password combination harvested / purchased elsewhere. As most people will use the same username / password combination for everything, I suspect the latter is more likely, in which case just make sure you vary the password and / or username for iTunes from your normal one.
If it's an apple 'hack', there's nothing much you can do about it other than ensure you change your passwords regularly.
I have to admin, I changed my iTunes account password this morning just to be on the safe side.
