After digging around in some wireshark logs of my btsync setup I found that btsync calls home to a server named: www.usyncapp.com.
I believe this is to gather statistics on which version is running where on what platform and so on. Especially important during the testing period I guess. Is the software still going to be doing this when it is final? And what info are you saving for how long and what purposes?
Number of Files
Numer of shared folders
A unique ID
What options are used.
This is the URI I found. (some info scambled)