LINQ demoOK - I had to get this quick demo up too:
That above is using C#3.0 with LINQ to search for all items from all feeds that were published after yesterday. The results are also sorted by title.
FeedFolder folder = FeedFolder.GetRoot();
DateTime yesterday = DateTime.Now.Subtract(TimeSpan.FromDays(1));
var allItems = folder.AllFeeds.SelectMany
(f => f.Items);
var items =
from item in allItems
where item.PubDate > yesterday
foreach (var item in items)
Note how none of that required adding sort or filter code to the object model! LINQ is totally awesome!