Never heard of it before you asked, and I am guessing neither has anyone else, since you have yet to get any responses.
So I did a search and found some definitions of the acronym:
1) Small Minus Big -- One of three factors in the Fama and French stock pricing model. SMB accounts for the spread in returns between small- and large-sized firms, which is based on the company's market capitalization.
2) SMB is an abbreviation for small and medium-size business.
3) The Server Message Block (SMB) Protocol is a network file sharing protocol, and as implemented in Microsoft Windows is known as Microsoft SMB Protocol.
Wikipedia also had:
Of these I am guessing that the most likely one is System Management Bus.
Of course, Stardock may have their own in house definition.