The full reprocessing of MODIS Land data was completed in May of 2008.
Processing of the newest MODIS Land collection (also known as Collection 5 or C5) commenced in September of 2006 starting with the first Terra data collected in February of 2000. Collection 5 processing of current MODIS data, or forward processing, began at the beginning of 2007.
Summary information on the C5 product changes can be found at the link provided above. More detailed information on the C5 reprocessing effort in relation to specific MODIS Land products can be found in presentations by individual science team members made at the January 2007 C5 Workshop.
Link to news information from the MODIS web site
Links to additional meeting and publication information from the MODIS web site