Well it was certainly a free book for me. I'd purchased Threshold along with the rest of the June 2010 Webscription at the end of May and when I went to the link Webscriptions recognized this, gave me a code, and discounted the book when I made my October Webscription purchase and included Boundry.
Very cool!
AdamV
and
Webscriptions/Baen Books!
Edit; Turns out Threshold is still in my TBR pile so now Boundry will go on top of it. Extra very cool!
BTW given the, sometimes, questionable "Deals" posted here I'd think this is as valid as most.