There is a comunity named “Open Data Information” we formed at Facebook, which is trying to collect any movements about open data. Please check the most recent information about Open Data, if you are interested in.

So, what is Open Data?
Wikipedia says, “Open data is the idea that certain data should be freely available to everyone to use and republish as they wish,without restrictions from copyright, patents or other mechanisms of control.”
The concept of open data is not new; but a formalized definition is relatively new by Open Definition,which is summarized in the statement that “A piece of data that can be freely used, reused and redistributed by anyone – subject only, at most, to the requirement to attribute and sharealike.”

Key features are:
Availability and Access: the data must be available as a whole and at no more than a reasonable reproduction cost, preferably by downloading over the internet. The data must also be available in a convenient and modifiable form.
Reuse and Redistribution: the data must be provided under terms that permit reuse and redistribution including the intermixing with other datasets. The data must be machine-readable.
Universal Participation: everyone must be able to use, reuse and redistribute – there should be no discrimination against fields of endeavour or against persons or groups. For example, ‘non-commercial’ restrictions that would prevent ‘commercial’ use, or restrictions of use for certain purposes (e.g. only in education), are not allowed.

Several national governments have created web sites to distribute a portion of the data they collect, especially USA and UK. They established the open goverment in 2009, broke new ground in open data. And they are trying to make an open vocabulary for easy data exchanging, as NIEM in USA, ISA core vocabulary in EU.

Now Japan government is also considering that it’s important to construct an open government with data open and transparency to public. Ministry of Economy, Trade and Industry has established a web site to distribute data and tried to collect ideas from citizens. Ministry of Internal Affairs and Communications has constructed a system named Gateway to Advanced and User-friendly Statistics Service. Also local governments has made their own best, like Sabae Data City in Fukui-Pref, Open Data Portal in Yokohama, Open Data Catelog in Shizuoka-Pref etc.

Links to those achievements in Japan:
Gateway to Advanced and User-friendly Statistics Service
Open Data METI
Open Data Ideabox
Sabae Data City
YOKOHAMA Open Data Portal
Open Data Catalog Shizuoka