"in the log file, there is no phone/user ID is stored"
Oh but they are sent too.
"And when "Location services" are on,"
i.e. When the hardware to track people is powered up, or in other words WHENEVER THEY CAN.
"it only can see the latest data about coordinates that needed to keep the database for speedy Assisted-GPS location corrections"
It's interpolated location with timestamps and all and none of this is useful in cell tower fix since it is a sample of location not a cache of a few of the most recent cell towers as it is on other platform.
"Whilst researching mobile data Allan stumbled upon a directory containing longitudes, latitudes and timestamps. Initial thoughts were that the data was just a few days worth of content, maybe from the cache. It turned out, however, that the data was around a years worth of data."
"The phone also recorded WiFi data including latitudes and longitudes, which weren't particularly accurate, along with mac addresses with timestamps. The pair hasn't quite figured out when or what triggers the data to be recorded.
"The phone was tracking around 100 data points per day and the file had been moved between multiple devices, initially starting on an Iphone 3GS. The start of this tracking seemed to be linked with the update to IOS 4. What's even more worrying is that the data wasn't encrypted."
http://www.theinquirer.net/inquirer/news/2045261/apple-iphone-tracks-movements#ixzz1KZVuDEwb