New version of Zotero is now available (though still in Beta form). Version 1.5b2 allows you to back up your library for free on Zotero's server, and thus sync your libraries across multiple computers. Another neat feature is that you can add a PDF to your library and ask Zotero to go and find all the reference information for you! It will capture part of the text and search Google Scholar (other databases to be added soon); if it finds a matching entry, it fills out all the metadata for you (author, journal, etc.) So far I have only actually gotten this to work a couple times (even when I pulled the articles directly from Google Scholar), but this is still a beta version after all. I am sure the main dependency for it working is where the data is found; journal webpage versus someone' s CV publication listing, for example. At any rate, when the journal can be found, it is quite a time saver!
Be sure to check out the new version. Below is a screen grab showing my local library and my library stored on Zotero.org.