According to the Federal Times:

Rep. Jim Moran, D-Va., is preparing to reintroduce a bill that would allow employees under the Federal Employees Retirement System to count unused sick leave as time toward their annuities. source: Federal Times

Last year Rep. James Moran, D-VA, long a champion of retirement fairness for FERS employees, introduced the bill that would provide credit towards retirement annuities for 75% of sick leave for those retiring within the first three years of enactment, and full credit for those retiring after three years. Unlike employees under CSRS under current regulation FERS employees cannot credit their unused sick leave toward retirement–so they lose it.

According to an August Congressional Research Service report sick leave abuse cost the government $68 million in lost productivity in the year ended March 30, 2006.

note: A few reports from Postalreporter.com readers state that USPS is threatening to issue (or issued) discipline to any FERS employee using excessive sick leave prior to retirement. Postalreporter has confirmed at least two instances where employees received Letters Of Warning after using sick leave 30 days before retirement.

Read more from the Federal Times or previous articles on the FERS sick leave bill