EyeHawk, wow you're right about the speed of third submission! I just got approved <img src="smileys/smiley4.gif" border="0" align="middle"> In a few hours it'll be published to the store!
Published: http://apps.microsoft.com/windows/en-US/app/dust-and-destruction/897a48d9-83f2-438e-b4a5-3a4018aefbf5
Edit: I'll list some changes I had to make, like EyeHawk I made it on the third try and the third approval was in less than 1 day.
To avoid snapping errors: Pause your game on snap (and make sure it doesn't conflict with normal game pausing as was my case), if you want your game to still work maybe you can mess with canvas size at runtime though
Make sure your description and images are final and fully detailed before submission, you can't patch it up without approval and the first review took me at least 4 days to find that out.
Try this to decrease load time: use lower res graphics on the intro layout (in my case I sized a 1366x1366 graphic to 512x512, and another 512x512 graphic to 256x256. Then you can resize them in the editor which will add a little blur but performance issues should be cleared), this is what held me up the second submission. If the ACK even gives a slight warning, you can probably count it as a failure to submit to the market.
It isn't too helpful from either the pre-testing or the review comments, but if you make sure the first layout loads as quickly and correctly as possible then you'll only need to worry about in-game bugs after.