First, about trading cards: now that the game is stable, I'm actively submitting the materials. Hopefully these will pop up before too long, but it isn't entirely up to me, since they're subject to Valve's approval. There are going to be more hoops to jump through, especially given a character like Ulfina. But you should get a notification when your cards appear in your account, so there won't be another announcement about them.
Meanwhile, we have another week of work that includes both some new content and some more tweaks. I believe we're hitting a reasonable level of polish! Meanwhile, I want to point out that the Arena Champion has a fancy new custom sprite:

Additions
Changes
I think this will be the stable version of the game for the near future, barring any critical hotfixes in case something surprising is discovered. The next update of the game will take a while longer, but should be a content update instead of polishing.
On that note, feel free to suggest any other characters you'd like to have custom sprites! I'm thinking that the steampunk wolf could use a top hat, for example. You can also feel free to request any other content and I'll at least consider it. Hopefully version 0.6.3 will be a nice chunk of new content taking the game close to its final form. ^-^