T-Mobile already admitted last week to using Carrier IQ's "diagnostic tool" on some of its devices, but hasn't been forthcoming on which phones customers should be wary of. TMoNews has published a screenshot from an alleged internal T-Mobile document which notes that the tracking software is "currently deployed on some of the following T-Mobile devices":

With some TMoNews commenters claiming that the software is also present on the HTC Sensation 4G as well, it's important to note that this may not be a comprehensive list. While listing the various types of issues the carrier is using CIQ to help address — battery performance, dropped calls, and application failures are all named — the document also reassures that T-Mobile "does not use the tool to obtain the contents of text, email or voice messages, or the specific destinations of customers' Internet activity." Those outraged enough by the Carrier IQ issue to switch carriers, however, may have an unpleasant surprise in store: the document clearly states that T-Mobile's early termination fee will in fact apply to any customers canceling because of the security snafu.