Get the new Dropbox for PC and Mac right now
Dropbox has added mobile features to the desktop versions of the app, and you don't have to wait until the newest version rolls out to take advantage.
Dropbox is almost finished wrapping up its work on version 2.1.x (the version you're probably using if you haven't upgraded). Releasing an experimental build allows it to get feedback from early adopters. This new build lets you automatically save screenshots, move files to Dropbox in an easier way, import from iPhoto, and get faster upload and download speeds.
Ready to check out the new version? To download a copy of Dropbox 2.3.12, find the link that matches your OS and install. What's excellent about this method of distribution is that you won't have to wait for tiered rollouts, or try to find a copy from someone else on the Internet.
After you're finished installing, just hit Control-Print Screen (or Command-Shift-3 or 4 in OS X) to let Dropbox know if you want all of your screenshots saved to the uploads directory. Unfortunately, you cannot set a specific key for taking and saving screenshots.
If you change your mind about screenshots, there is an option to toggle it. Getting there involves clicking the Dropbox icon, then the cog icon, and then Preferences. This is a few extra steps from the previous version of Dropbox.
Curious about the other new features? "Move files to Dropbox" will add an option to your context menu for easily migrating files. The "Import from iPhoto" feature only works with iPhoto 7.0 or higher. If you choose to sync iPhoto, albums and events turn into Dropbox albums so you can easily keep track of and view your pictures.
Backing up photos has been a major focus for Dropbox recently. Do you think it's the right area to focus on, or should its efforts be funneled elsewhere?