My 2 cents:
I don't know what exactly they are planning. If it's like something the DM can give to certain players like a boon, it's okay. But it's not needed at all. According to what I expect of WotC it will be a +1 to damage or whatever boring thing. You can do that quite okay without cards. If it's something the players can bring to the table and use on their own accord, it's horribly. I never ever want to have such a thing at my table. Looks like they're turning it into a kind of MtG card game. Power and Monster Cards are all fine. They make playing easier. But this thing would be the first but fundamental thing I'd really hate about 4e.
Hopefully someone at WotC reads this and the news where only a test.