The second time is the good one! Microsoft has just certified Ocell and it’s ready to publish at the Marketplace. You should see it now in your Market app, or you can click this link on your PC.
This version of Ocell includes support for multiple accounts, custom columns (just like TweetDeck!) and conversation view, and of course all of the common features of a Twitter client.
So, if you’re interested in Ocell, it should be available in your Marketplace today or tomorrow.
PS: A big thank you to Asinensis in Flickr. He gave me permission to modify one of his photographs to make the Ocell logo