Well, as far as I can recall, the Cardassians lost their ships at the Azure Nebula when the Borg basically obliterated everybody there minus a few exceptions. In the novels, there is no mention of what has happened to Cardassian worlds. I find that incredibly ironic, actually, and very symmetrical in the spectrum of events in Trek literature and television. Sure, the Dominion was bent on destroying the Federation, yet the Cardassians pay the price. Now, the Cardassians join the Federation to stop the Borg (albeit the number's few in comparison), but it's the Federation and its allies that pay the price. As General Martok would say, "it'd be poetic justice". However, with the rise of the Typhon Pact, President Bacco was looking to extend the signatories of the Khitomer Accord nations, and wanted to include Cardassia as a part of that expansion.
At least, it's how I remember it. Someone can correct me if I'm off.