NBC Today show
If you aren't already in Royal Wedding overload, you might want to look into getting the newly unveiled iPad Royal Wedding app available in iTunes now. Put together by the NBC Today Show, it contains photos, interactive activities and all the latest information so that you won't miss a beat, and the good news is that it is free. The iPhone and Android apps will be available shortly.
In addition, NBC's own wedding website, the Windsor Knot is full of tidbits of information coming out daily, so that you'll always be on the cutting edge of news. It appears that the whole Today show gang will eventually be in place around the city of London on the wedding date to share the news with all of us. Coverage starts at 4 AM and continues until 11 AM Eastern time.
A excellent summary of the schedule of all of NBC and its affiliates' broadcasting can be found here. You might want to bookmark it if you are in the US, wishing you were in London on the big day. You know you're going to want to have a ringside seat!