It isn't only iOS devices that do this. All operating systems probe for SSIDs that they have been previously associated with, thats what makes devies like the WiFi Pineapple possible [0].
However, Apple devices do do "optimization" to get on the network quickly. If you previously associated with a SSID, it'll get reconnected much faster.
I had to install aircrack-ng. Upon doing so and watching for about 30 minutes, I saw my MacBook Pro and iPhone 5 both leak an uncomfortable amount of probes for SSID's my devices have attached to. The thing is, quite a few SSID names are unique enough it nailed the specific devices I had attached to and through Apple's geo-coordinate database, their coordinates.
If the author is reading I just sent a pull request for a defect in the 'SSID Search' page. Thanks.
I'm curious to know if this is an iOS only issue. It seems to me that any device that remembers past SSIDs would look for them actively. That way the user gets on their preferred network whenever it's available. Then anyone with access to a database with GPS coordinates for base stations would be able to achieve the same effect, no?
Whether or not your phone is disposable seems not to be relevant to this attack, such as it is. Your device will still leak information suggesting where you have recently been.
Storing personally identifiable data about people is covered and controlled by EU Data Protection law. Broadly, you have to have a legitimate, legal, proportional reason for storing personal data on people. You probably need their consent.
Perhaps not for honest folk like yourself, but there are obvious ways that it could be used for evil - set up an access point with the same name and MAC address to sniff traffic and/or perform all sorts of man-in-the-middle attacks.
Headline is hyperbole. According to the linked page, iOS devices leak some network information and it may be possible to analyse this to establish where the device's owner lives.
as far as I remember this is a feature, the wifi connection stack on osx is trying to connect to recent wifis first with the mac address because that is much faster than trying to get a new lease and so on
It also causes occasional IP-address conflicts. Had this happening before and traced it to an iPhone using an IP-address it did not have a DHCP lease for.
[0] http://hakshop.myshopify.com/products/wifi-pineapple