It would be useful to be able to see which suggestions have changed since you last opened them (ie suggestions that you haven't opened, or that have had a status change or comment added since you last opened)
SixLinks Developers' response:
This would be fairly expensive (in terms of server load), and isn't trivial to implement. Note that the updates to suggestions you're following will show in the My World/Following page. (That page doesn't work yet - but it will soon!)
Let us know with your votes and comments if this feature's something you want!
Update: We've now added filtering that seems to address this issue to people's satisfaction. If you're not satisfied, leave a comment, or open a new suggestion.