This link gives a good overview of it.
http://en.wikipedia.org/wiki/Progres...pensationalism
It began in the 1980s, and is held generally by Calvinist-Dispensationals. Blaising and Bock, and Saucy, have published books describing it. John MacArthur, though he would probably not use the label, would fall into the general category of PD. There are variations within PD, but the major differences from classic dispensationalism include:
1. "for traditional dispensationalists, the only relationship between the dispensations is chronologically successive." PDs see the present age of grace as a vital link in God's plan of redemption, not just a parenthesis.
2. One New Covenant "with an ongoing partial fulfillment and a future complete fulfillment for Israel." (Some Classic dispensationalim authors saw two separate new covenants, one for Israel, one for the Church, or other variations.) "Progressives hold that while there are aspects of the new covenant currently being fulfilled, there is yet to be a final and complete fulfillment of the new covenant in the future. This concept is sometimes referred to as an "already-but-not-yet" fulfillment."