I believe the system automatically puts the new questions on top (someone from SCN team will need to confirm this though, just a feeling I've got watching a specific tag so far). The prerequisite is that community members are using the right tag, if the right tag exists that is.
The topic where I'm most active is SAP Solution Manager so I navigate to the primary tag using Community - Browse the community - filter by product and in the end click on SAP Solution Manager. That way I end up on the SAP Solution Manager space within the new community. There I can check recent blogs/q&a's given they tagged them in a correct way.
It might be that in some tags, if you use the search function, almost no new content exists so far and you find only entries that state "archived". I've read in some other posts that questions can be under moderation so a moderator would have to confirm that the question may be posted at this moment still.
Hope this helps to some extent,