It's just the white circle with WP in the midle and WPCentral text underneath. What is strange is that being supposedly transparent, it has a gradient background.
Yeah your device hasn't pulled down the live tile just yet, glad to know that mystery is solved!
The SDK allows me to use a scheduled pull tile so it won't refresh until the OS kicks off your hourly tile refresh. It should happen about an hour after the last time you used the app, but I have seen the OS get a bit confused and take a bit longer (can I suggest doing a full turn off/on then get back to me in a couple of hours )