It was just announced (say 20 minutes ago) on CBC that while there were rumours going around it was Sanchez because it was apparently a Spanish cyclist - in fact it was a Spanish female cyclist (who was tested on July 31 then pulled out unexpectedly and flew home, apparently for personal reasons).
i can't imagine how a spanish rider can get away with doping, given the stringent and rigorous testing done by their federation. really, who's going to be falsely accused next, contador?
"Spanish cycling federation secretary general Eugenio Bermudez accompanied Moreno to the drug test in the Olympic village. He said she emerged from the test crying and asked to return to Spain immediately, citing an anxiety attack."
-- I guess doing a dope test knowing that you have doped is quite a stressful experience.