Synthetic Biology is not a new term.  In Laying the Foundations for a Bio-Economy[1], Rob Carlson writes:

“‘Synthetic biology‘ was, until recently, a phrase found in literature at least decades old (Szybalski and Skalka 1978), first appearing nearly a century earlier (Keller 2002), but not used much in the last thirty years.”

Drew Endy tends to emphasize that Synthetic Biology is development and application of engineering principles to the genetic engineering technology stack: DNA sequencing, synthesis, PCR + part & measurement standardization, insulation, and abstraction hierarchies for biological systems [4].

Other people use synthetic biology to mean progress in building a completely synthetic cell.

Craig Venter sort of ignores the “hardcore” SB engineering dogma and just talks about “Synthetic Genomics” (also the name of his company) as the ability to synthesize a genome de novo.

Of this set, I’m most excited about the hardcore SB dogma, which to me is the most visionary and novel.

[1] http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2398717

[2] http://fora.tv/2008/11/17/Drew_Endy_and_Jim_Thomas_Debate_Synthetic_Biology#chapter_04