cs5 and 5.5 allow you to export library items as .swc files or "compiled clips" these take up one spot in your library, but contain the ENTIRE .swf they're compiled from... this means you can have entire games in one library item.
We used .swc files to make each level in abobo's big adventure, then imported them into a master file. It made library management a dream and compile times awesome because those clips are "pre compiled" meaning they don't have to be compiled again at runtime.
If you're not using .swc files, then you're missing out on a huge new feature of Flash.
BSTHEDOG
I have it but i couldn't tell you much about the technical stuff. In my mind, its almost the same as CS4 for anybody looking to animate with it.