To me Dropbox seems like it's a pretty simply and mature product feature-wise. Have they announced that they're expanding into other products? I just hope they won't bloat Dropbox the way that some of these one-main-feature softwares were inflated in the past (ICQ, etc).
edit: I guess what got me thinking about this is that I'm reading the book by Google employee #59, and Google had a working search engine and they were building their own hardware with less than 100 employees. Just not sure what Dropbox can do with 400+ since their product is a lot simpler and they're not dealing with datacenters, though maybe it makes sense if these people are mostly doing marketing and sales.