One would think that using the php include function to include a page with the rss feed and formatting would be the simplest route; either way you'd have to do something similar to insert a js island (if they where available).
LastRSS has a cache with it to cache content to halt pounding on feeds.
Also, the beauty of RSS is that you can customize the output, unlike js islands.
An example,
this can become
this with some simple formatting/css work (i know the look is ugly, i just threw it together as an example)
