They've hung out the 'Closed' sign on our old friend MobileMe, but Apple is still giving you the opportunity to download iDisk files and stored pictures for a limited time. In fact, if your iPhoto library is linked to your MobileMe account, iPhoto will take care of copying your galleries for you.
Just launch iPhoto (version 9.2.2 or later) and the dialog box above will pop in. If you click Learn More, you'll end up at Apple's tech note; don't worry, you can come back and get the files later by relaunching iPhoto or by clicking the MobileMe entry in your iPhoto source list. When you do, iPhoto will download all your galleries into a "From MobileMe" folder. Handy! Note that if you're slightly behind on iPhoto versions (before 9.3), you won't get your Aperture-uploaded galleries this way.
Of course, Apple's Photo Stream sharing can ease the galleries pain a bit; there are also many online photo options, including the free Pixi.me and freemium services like ThisLife, Flickr, Smugmug & Shutterfly. You may want to be a little selective with your photo site choices; as we've seen, company size is no bulwark against obsolescence or business shifts. ZangZing recently announced it is going dark (only months after encouraging MobileMe users to switch over), as did Picnik and Kodak Gallery before it. (Ars Technica has a great post up about the Kodak to Shutterfly migration in progress.)
With iDisk's archives still accessible for a bit, you can still download your MobileMe websites if needed and rehost them elsewhere. Companies like LifeYo and MacMate will happily host your site for you, although you may lose some features like legacy comments. MacMate just added a Galleries feature to match up better with the late MobileMe hosting package.
For a nice video rundown on the farewell to MobileMe, check out TidBITS' session from a couple of weeks back.