Anyone who knows how to track iOS app downloads (through web ads) without UDID?

I have thought it becomes impossible especially if the user comes from website to AppStore. But a company called WDA seems to make it possible.

http://www.lovefortech.com/2011/09/17/developers-track-ads-on-ios-and-android-devices-without-udid-with-apptracker/

http://wda.us/press/track-app-downloads-from-web-ads-without-udid.php

I have some ideas but I'm not sure which is the best way.

1) Cookie: iOS apps cannot access the cookie in Safari. 2) Shared Local Strage: Is there any shared storage which can be written by Safari and read by native iOS app?

iphone tracking ios5 udid
Edit
Report