From what I've read about the Hubble, that seems somewhat unlikely but not impossible. From what I've read, that would require refocusing the mirrors to look at something much closer than stars. There's always a risk that the focusing motors would get stuck and leave the Hubble crippled. There's also the issue of slewing the Hubble fast enough to do satellite to satellite imaging. If you're trying to imaging another LEO bird, the slew angle rates would be pretty high. The Hubble has to slew itself entirely aim at something. It'd be a lot easier to do that with a telescope with easily moveable optics. It'd be a lot easier to image a satellite out at GEO than LEO.

While it is possible to do satellite to satellite imaging (and it has been done), I really don't think I can discuss anything specific due to classification issues. I'd be very surprised to learn that it has been done with the Hubble is all.