The dropbox source for linux isn't quite what you think it is. Dropbox for linux consists of two parts: a server, which communicates with the dropbox website; and a client, the frontend part that you see. Only the client is open source. Without the closed source server being compiled for armel, we can't run dropbox.

Personally, I just use the web interface if I need to download files from my dropbox, or upload files to dropbox. Of course, this does depend on you having an Internet connection, slightly defeating the purpose. For now, you'll have to look elsewhere for file synchronization.