Stardock have re-released Total Annihilation on Impulse, their digital distribution platform. Interestingly, they've has promised "ongoing updates" for it. Brad Wardell said, "We're treating Total Annihilation similarly to a newly released title with ongoing updates wherever possible."
Total Annihilation ships with its expansion, Core Contingency. These were the spiritual ancestors of the first Supreme Commander game, and their unique strategic quirks were much referenced in the massive comment threads for both of my SupCom 2 vs StarCraft 2 articles from last week. Stardock say they've revamped multiplayer connectivity, added a new launcher that'll help you get it running on your PC, and that it "includes easy access to tips and tricks for getting the most out of it." With permission from Atari, they want to eventually incorporate user created content from fan sites and integrate it with ImpulseReactor, their developer tools that hook into Impulse.
You can buy it here for £8/$12.35.