They separated the topology from the discovery, so it can be imported at will rather than automatically. Topology: Layer 3 is going to be the topology at a layer 3 level of course and layer 2 is for layer 2 topology on your devices. If you want the topology data, and select those "interfaces" it will be polled with the regular polls now rather than with the discovery.
Umm, OK, but that didn't really help much. What all data is gathered? Where is it reported? Where can I get so deeper detail regarding this interface? I'm sure I am missing something obvious.
I don't believe there is any real documentation that answers your question but I will mark this for the PM to comment on and hopefully get some answers for you.
Here is a video and blog from our Head Geek that both detail topology. This thread also contains a link that might of be interest as well. You might already be familiar with this information but thought I would share in the instance that it might help answer a few questions until the PM can get to this.
