TrackObjects solves the problem of following and identifying objects over time and assigns a unique ID to them. Useful when you get blobs from some object detection routine that doesn’t care about IDs. Send your blobs through TrackObjects to get a stable result.
If you want to track objects other than Vector2 or Vector3 you only have to provide an implementation of the adaptive Distance node for your datatype.
Just to put it into context to @joreg 's patch - it will probably perform slightly slower, but it is much more stable in practice. Also, it does not rely on an actual Distance function for the feature you want to track, instead you are asked to fill out a delegate that calculates said distance (which is only a measure, of how far apart two things are from each other, not just in space, but also in appearance and other intrinsics).
In addition to that, you are also asked to provide a simple Smoothing delegate, as this smoothing is vitally important for the tracking algorithm. This is super easy most of the time, a simple Lerp should do it for most cases.