Hi Alan,
Thanks for that link. As I thought Amazon S3! Thought it might be somehow seeing as how they are giving away so much space. Do you think that they will have had to get some kind of license agreement with Amazon to do this though as I know that one of the Amazon dev crew once said on the forums over at AWS that they were not too sure what they would do if someone started using the S3 service as an online backup service offered to users. I guess they would have been in touch first?
Also this does work very very efficiently. Nice to see that the files are first stored on your machine which means that you can re-name them very easily because using the standard S3 service there is no way (that I know of) that you can re-name files without deleting the original first and then re-uploading the new name version of the file, apart from I think it is one of the applications that allows uploads to be sent to the service having their own programmes on the S3 servers to handle this but at a charge of around $1 a month I think.
Seems like a very nice idea but I’m not too sure how safe I feel it to be with regards to security. Obviously your files are being stored somewhere that external people have access to and so I’m not sure I would ever use one of these services for anything that is personal unless I had created the application myself, which of course I just don’t have the knowledge to do!! 
Great idea and fantastic implementation though. Will probably use it for non mission-critical files at the moment for transporting between one place and another.
Any ideas on pricing if people want more than 2GB storage space. I see from the document that you linked to that the Techcrunch users got given 5GB instead.
Best wishes,
Mark