Update: Apple is NOT Tracking iPhone IMEI
So all the speculations that the URL embedded into the Stocks and the Weather widgets, which apparently included your iPhone’s equipment ID (coverage below) was used by Apple for tracking has been squashed by a German site Heise Online.
According to Heise Online, the iPhone doesn’t send an IMEI (the iPhone’s unique identifier) back to base but actually is some application specific information and does not have any person identifying data.
The main reason the original news/rumor was convincing was due to the fact that it was supported by a screenshot which shows the URL string being called and it had the code “IMEI”. However the German site goes on to confirm while the code says “IMEI” the actual IMEI is not being transmitted after comparing the strings with the test iPhone’s IMEI. Based on some more investigation carried out by Rene at blog docpool, these IDs are in fact identical in all iPhones he has tried.