US Nationals for all levels novice and above are always held after the Jr. Nationals and in a different location. It's my understanding that the regular US Nats in January help determine the remainder of the international assignments for 2008-2009 and also for the first set of 2009-2010 assignments. I don't think the Junior Nationals are used quite for the same purpose since those levels don't have as many international opportunities.
JNs (this year in Lake Placid) do afford the opportunity for the Young Internationals offers at the Novice level and to get skaters enveloped on the development team.
As announced June 24, 2008, U.S. Figure Skating's International Committee and Athlete Development Committee came up with a new set of guidelines that will now allow any member of U.S. Figure Skating to participate in nonqualifying competitions outside North America, provided they adhere to the guidelines and policies. This has officially replaced the Young Internationals program.
In addition, the Developmental International Team includes mostly skaters at the following levels: novice, junior and senior (who skate at U.S. Nationals); however, spots are available for Intermediate-level athletes who place 1-3 at the most recent U.S. Junior Figure Skating Championships. :agree:
FYI, here's the event page for last year's U.S. "Junior" Championships (Nationals for the Intermediate and Juvenile levels) that was held in Salt Lake City -- video and articles, photos, etc.: http://web.icenetwork.com/events/detail.jsp?id=34518