Best Vacuum Flask with Push Button Pump

Not push-button, but best for your purposes.

http://www.amazon.com/Nissan-FBB1000-Stainless-Steel-Insulated-Briefcase/dp/B00009V4FM

The Thermos beverage dispenser keeps hot water warm for 8-10 hrs, and has a push button on top:

http://www.amazon.com/Thermos-Insulated-Service-Vacuum-Metallic/dp/B00006WNRZ/ref=sr_1_1?ie=UTF8&qid=1315101625&sr=8-1

I have owned a variety of insulated coffee mugs and bottles over the years. The ones from Nissan/Thermos are good, but the best in the bunch are from Highwave (highwave.com). The JoeMo TC Tea mug (amazon.com link) is the best pushbutton vacuum tea mug in the land. They sell all sorts of interesting glass, steel, and stoneware products for water, coffee, tea, beer, and wine. The only loser is their LED Light mug: the light works, but it's a really cruddy design. All of their mugs and bottles are top-notch.

Are you talking about the kind that plug in?

I misunderstood your request the first time....

You seem to be talking about an Airpot. Those are typically used to dispense coffee, but hot water should work fine, too.

Zojirushi makes some products that are specifically designed to heat and then dispense hot water all day long. They are designed to have hot water instantly available at a precise temperature. The "hybrid water boiler and warmer" models have vacuum insulation and are very energy-efficient. They're also pretty fantastically expensive ($150 and up), so I don't know if that's your cup of tea.

Zojirushi also makes the airpots. If you have a good source of boiling water and don't care about the water temperature slowly dropping during the day, those should work fine.

Other Z products have been cool tools in other categories several times. Good products.