If you are a small nonprofit under $25,000 and had not filed a 990 or the 990-N postcard with the IRS in the last three years by May 17, 2010 you were at risk for losing your status. However the IRS is willing to work with these small nonprofits, so go ahead and file, even if you did miss the deadline. Instructions to file and the IRS efforts to help the small nonprofits keep their status are on the IRS website in the charity section.
The impetus behind this provision is to clean up the IRS records. It is suspected that there are many nonprofits on the IRS listing that ceased doing business years ago. There is a good detailed article on this topic at Nonprofit Newswire (which is a great daily newswire service to subscribe to)
In the week prior to May 17 we looked up some area zip codes and contacted local nonprofits we knew, that were on the list in danger of losing their status. They were unaware of the IRS Form 990-N. The most common reason was that the Board Members had changed and it is likely that any IRS notifications went to a former Board Member. See this link to look up your area