I didn't know about this until today, but sounds like a good idea to me, especially if it raises the profile of the conservation needs of the Sparrows.
The World Sparrow Day (WSD) is being celebrated on 20th March across the globe to raise public awareness about the decline of Sparrows and throw light on the problems faced by the family in their daily fight for survival. The World Sparrow Day also celebrates the common biodiversity around us.
The first World Sparrow Day was celebrated on March 20, 2010 across the globe to celebrate the beauty of the House Sparrow. National and international organisations, NGOs, clubs and societies, universities, schools and individuals across the world celebrated the event by organizing awareness programs.
House Sparrow (Source Unknown)
World Sparrow Day also has a broader vision to provide a platform where people working on the conservation of Sparrows and other common birds can network, collaborate and exchange conservation ideas that will lead to better science and improved results. It aims to provide a meeting ground for people from different parts of the world to come together and form a force that can play an important role in advocacy and in spreading the awareness on the need of conserving common biodiversity or species of lower conservation status. Check out the World Sparrow Day website.
BTO Garden Birdwatchers have charted the fortunes of House Sparrows every week since 1995. On average, during this period, almost one in four British and Irish householders who used to see House Sparrows no longer have them visiting. However, there have been big regional and seasonal differences (further details here).
I'm really enjoying having House (daily) and Tree Sparrow (occasionally) visiting my garden in North Duffield. I'm going to hopefully get some sparrow terraces put up around the house to try and encourage them to breed here too. These boxes are readily available (e.g. see here).