I'm having the same problem also. Error says that I'm either blocked by a firewall (I'm not) or not connected to internet (I am) or game server is down or clear my cache (I did, several times.) Glad to see its not just me and that Yahoo will probably fix it soon. Gotta say however that it is a big let down on yahoo's part to not address this issue after having the problem for several days. Nothing like an info box on the main game page to say "Sorry folks, our game servers are down while we resolve an issue, or work on improvements to better performance, etc"
I get that this is free - but so is Facebook, Twitter and a gazillion other communities which generate income and let folks know when it's down and why. Yahoo isn't running this thing without pulling income from advertisers so us community folk must be helping them rake in the bucks somehow. We deserve an explanation. Gotta tell you - I combed the internet today for a good spades replacement online community and didn't find one. If there HAD been one, Yahoo woulnd't have seen me again. AHEM... all you programmers out there ;)