The American Jobs Creation Act of 2003 (H.R. 2896) contains a provision that would reduce the depreciable life for leasehold and tenant improvements from 39 years to 15 years for property placed in service in 2004 and 2005. The bill was approved by the Ways and Means Committee and could come up for a vote in the full House soon. H.R. 2896 is primarily focused on overhauling the rules governing many facets of the taxation of multinational corporations, but it also contains some domestic reforms that simplify business taxation while enhancing productivity and increasing jobs.
For more info on leasehold and tenant improvement, see: http://www.REALTOR.org/GAPublic.nsf/pages/mymtaxes#depre