While I agree with the core of your comment - a disagreement isn't really news - your comment is two adhoms and a contentless snark, so I downvoted it.

1. Who shared or commented on an item. The search above I knew I had liked the picture, so I constrained the search to only things I’ve liked.

But I didn't know Robert Scoble liked the picture, so it wouldn't help me find it.

2. How many comments or likes are on an item. Good if you happen to remember it, but also something Twitter could add - search filtering on how many @replies/retweets something got.

3. What was said in the item. You can't comment on a tweet, but you can @reply/retweet or just tweet again moments later with your comment. It's not the same as friendfeed but it's not dramatically far away. I'm not convinced it's such a big difference that twitter can't overcome it with search improvements.