BeefJack writes: "We reported yesterday that there had been problems reported on the Xbox Live Marketplace. After a little investigation we found a post on the Xbox Live Operations Blog giving some more information.
From the post it appears that the marketplace problems are primarily dealing with the error codes: 80004004, 807B01F4, and 8015000a. It may also show that you haven't purchased content when you have. However, we are assured in the blog post that we have not lost our purchase."