Google Buzz post can gather lots of comments quickly turning them into "skyscraper" posts. Google’s making some changes for comments to get collapsed in Buzz. In past, old comments were sometimes collapsed, but new comments were always expanded. Now, new comments, may be collapsed as well. Here’s how it'll work:
“If there’re 3 or more previous or new comments, we collapse them into a group. We leave latest previous comment (from before your last visit) expanded to give you context.
We leave last two new comments (since your last visit) expanded so you can get a taste of ongoing conversation and decide if you’re interested.
If there’re enough previous and new comments, we collapse them together into a single line to save space. You'll see names of some of people whose comments are collapsed, to help you decide if you might be interested in diving into the conversation,” explain Google.