Plugin save_post action and excerpt auto generation/creation

I’ve been poking at this for a couple weeks now. I’m trying to make it so when I save a post that it will automatically generate an excerpt and fill in the field in the database. This makes a lot more sense to me than generating the excerpts on the fly every time. It also would allow me to easily plug the excerpt ino the meta description field for a single post page.

Unfortunately I can’t get it to work. I’ve tried a number of ways to update the database (using other plugins and core code as examples) but nothing seems to work. I’m now starting to wonder if the save_post hook is actually getting triggered.

Any ideas or pointers would be greatly appreciated. Even better would be a link to an existing plugin that does this already.

Thanks,

jivany