People often ask me, "Alice oh Alice, when oh when will another I get to install another download client? I've got everything from GameTap to a mint condition copy of the very first version of Steam (preserved in a mylar directory, of course) but I want more." Good news, chum-o: GOG are about to open up the beta version of their Galaxy client to everyone.
Unlike most store's download clients, mind, Galaxy is entirely optional. GOG games still come as DRM-free installers but if you do fancy auto-patching, friends, chat, stats, achievements, matchmaking, and whatnot, hey, give it a whirl.
You're familiar with the basics of a digital game store download client, I'm sure, but GOG Galaxy does bring one interesting novelty. It enables cross-platform multiplayer with games using Steamworks' multiplayer bits, if the developer adds support. The cross-platform launch lineup is only a handful of games, but I hope to see it in more.
One nice feature in GOG's future Galaxy plans is an easy way to roll back patches, restoring games to their earlier state if you don't like something a patch does (or breaks).
They'll be setting their old GOG downloader client out on an ice floe, stopping updating it but not intentionally disabling it. Plain old downloads will, of course, stay.