Vietnamese New Years (aka "Tet") is a drawn-out affair comparable in importance to Thanksgiving or Christmas in North America. The New Year itself is on the 29th of January (it varies from year to year, being lunar), but festivities and family reunions won't end until around February 3rd. The big party is tonight, the evening of the 28th - New Year's Eve! It's essential to start the New Year with a beautiful kumquat tree and/or flowering branches at your house. It's very strange to see a six foot tall tree flapping about on the back of a scooter, but the city has been graced with thousands of them. Today, people are rushing about like maniacs making the appropriate purchases, but the stores are steadily closing down. I expect that tomorrow the town will be very quiet - it's a day to be spent with family.
This seems like a good article if you want to learn more about Tet.