From the press release at www.webscriptions.net:

September 7, 2007—Wake Forest, North Carolina: Baen Books is proud to announce that it has concluded a deal to release electronic versions of select Subterranean Press titles. The titles will be available both individually and as part of a separate Subterranean Press program available at Baen's e-publishing site, www.webscriptions.com.

Read the whole press release here.