Last week, an Android study  by several people from Intel, Penn State and Duke Universties was published that showed how 15 popular applications in the Android Market shared location data with advertisement servers, while 10 shared unique identifiers with them, as well. Additionally Eric Smith (University in Lewisburg, Pennsylvania) published an Iphone privay study  on October 1st, 2010 and shows where and how the iOS shares UDIDs with whom, and how the UDIDs are being used.
The iPhone’s UDID is eerily similar to the Pentium 3’s Processor Serial Number (PSN). While the Pentium 3 PSN
elicited a storm of outrage from privacy rights groups over the inherent risks associated with the sharing of such
information with third parties, no such concerns have been raised up to this point regarding the iPhone UDID. As
UDIDs can be readily linked to personally-identifiable information, the “Big Brother” concerns from the Pentium 3
era should be a concern for today’s iPhone users as well.
 Android privacy study (2010-09) by William Enck et al.