Facebook saves the page state after modifying it dynamically (ie clicking on "Older posts" to load up some older entries, click a link, and your browsers back button; it just works). We did some work at FriendFeed to make sure the state is saved as new entries stream in and I'm happy that Facebook took a similar approach.
I sold my first item on craigslist today. I almost chickened out of the exchange...suddenly it felt like I was just asking for trouble giving out my address. I was just going to not answer the door when a very nice woman and her young son knocked. I'm glad I went through with it.