Dropbox is a new way of synchronizing files across your PCs that just works.

Looks like a well thought-out service and it was a fun presentation. The only thing I don't like is that you have to install software on your PC which, presumably, always stays resident. I'd personally rather use a web-only service to back up my files, plus I can't imagine corporations entrusting their files to a third-party startup. I'm also impressed with but suspicious of how quickly changes were mirrored - there must be a lot of heartbeat traffic with the server. Another my concern here is privacy. They need to make it absolutely clear what they do to protect your files, who has access to them, and so forth before it can become useful in businesses. If the servers are USA-based, then regardless of the company's privacy policies I wouldn't trust my data to them.

Well, it will be free. At least the beta will be free.