One of which is compatible with nearly every AC power brick out there (in general not even requiring plug adapters, it's a rather cute design) and the other two are compatible with plug adapters (every DC-DC "auto-air" power converter I've owned in the past 7 years has handled both empower and cigarette-lighter plugs)

So two real standards, one DC and one AC. I think the AC way looks like the future, at least on long-haul.