How do I identify Asura gates at a distance?

If I get within a few feet of an Asura gate, text will appear telling me where it leads. However, this is not very convenient in places like Lion's Arch, where there are many gates.

Is there any way to identify Asura gates on the map? Failing that, is there any way to identify them from far away?

Unfortunately, as of release, there's currently no label on the World Map or anything else that marks the Asura Gates.

However, in Lion's Arch, the NPCs standing near each gate are indicative of where the gates go to. In the image here, you can see 2 Norn at the left gate to Hoelbrak and at the right gate, 2 Charr at the gate leading to the Black Citadel. So at least there, you can just glance at the NPCs standing at the gates rather than having to run all the way up to them.

Just to update based on Brian's comment:

Today's game update includes the following change: "Lion's Arch: Map-marker tooltips for asura gates now state their destinations." (April 30 2013)

Instead of needing to approach the gate or needing to take visual cues from the surrounding NPCs or color of the portal, you can roll over the portal on the minimap or world map and the second line of its tooltip will tell its destination.