The Internal Revenue Service is planning to increase fees to any non-profit organization seeking to form or convert to 501c3 status. Genealogy societies in the U.S. typically file as 501c3 organizations. The application fee to become such a tax-exempt organization will double from $150 to $300 on July 1, 2006.
The IRS web site explains:
The Office of Management and Budget has directed federal agencies to charge user fees reflecting the full cost of providing goods or services when the benefits to the recipient otherwise exceed those received by the general public. Many IRS user fees had remained unchanged for years; the new fee structure more accurately reflects the resources expended. Although the fees have increased, the Service continues to be sensitive to the financial resources of smaller organizations.
You can read more at http://www.irs.gov/charities/article/0,,id=151893,00.html.
This is obviously a hardship on small societies with limited funding. If you are thinking of filing, you might do so before July 1 when the application fees double.