During one drunken bottling session, I managed to bottle over half of a five gallon batch before I realized that I forgot to add priming sugar. I was afraid the brew would get aerated if I emptied the bottles, but it turned out fine. To keep from aerating the beer, I sanitized a smaller pail, then slowly poured bottle by bottle into the pail, tilting the pail so the beer poured on the side without splashing. I then emptied the pail slowly into the bottling bucket as needed (maybe twice), trying to minimize splashing. I had one from that batch just last weekend, thought it was great, and had completely forgotten my error until I saw your post. In other words, there was no noticeable difference, although I recomend avoiding things like this if you can. If you take precautions, you'll be fine, and it will be a lot better than flat beer. I'm glad I keg now, though. I just tapped my first homebrewed keg last night, and that is a lot better!