I don’t use it frequently, but I just noticed that the WordPress.com feed reader has some functionality to concatenate and display multiple posts together for feeds that update relatively frequently. I like the fact that there’s a little less cognitive load in changing contexts from one source’s posts and those of others which have longer inter-post times.
While some don’t like feeds that aren’t ordered temporally, this seems like a useful compromise when looking at feeds with large numbers of different sources.
This is somewhat reminiscent of the way Tantek Çelik concatenates likes within his homepage.
Whether within a stream of posts on a personal site or within a feed reader, this UI pattern is very subtle, but incredibly useful.