Just finished building my all-in-one arduino with the wifi addon. LOVE IT! I have one strange issue though.
If I power up the clock cold, it goes through the calibration cycle and then starts showing the time as 12:35. If I log into the Wifi control panel, it has the correct time from NTP.
Sometimes if I let it sit, after an hour or so it might catch up - but otherwise the only way I've been able to get them sync is with the main clock powered on, unhook VCC to the wifi module and plug in it back in. As soon as the wifi module boots back up the clock updates and shows the correct time.
That looks perfect. Every time the "Time last update" gets to 60000, it should send a time update to the clock. 60000 is 60000 milliseconds, so that is once per minute, which is much more often than needed.
If you can watch the summary over a few minutes to make sure that the time is read from the server reliably ("Time according to server" shows you what came back), and that the "I2C slave" is reliable and does not disappear.
If you have a scope, there's plenty to look at, but one thing at a time...