It seems like that the MSDN release of Windows Longhorn Build 5048 has been delayed to next week.

From Andy Boyd, Program Manager MSDN & TechNet Subscription Online:

I have it in our system but it is currently on hold. I do have a firm go-live time and date, which I cannot announce as yet until some other communications get handled. Yes, I know it's frustrating, No, there's nothing I can do to speed things up. Check back next week for more news, I'll post a note here, on my blog, and update the RSS feed when the bits are live.