My COBRA benefits have been canceled without notification or cause. Do I have any legal recourse?

You may very well have recourse.
There are circumstances under which your COBRA coverage would end, but you haven't described any. If the COBRA company that you refer to is a third-party administrator that is "running" the employer's COBRA procedures, have them check with the insurance company as to why your coverage is cancelled (in addition to you checking further).
Not only should your coverage still be in effect (absent some other circumstance that you don't mention), but it's possible that you should be eligible for the 65% reduction in premiums that was enacted a few weeks back. You don't say what the reason for your termination of employment was, but if you were involuntarily terminated after August 31, 2008, and you elected COBRA starting 12/1/08, then your premium would go down by 65% effective March 1, 2009. You should have received notification of that change, and certain forms that may need to be filled out.
However, if your coverage legitimately ended as of 12/31 for some reason that you don't mention (such as becoming eligible under another plan), then the premium reduction, obviously, would not apply. (In addition, if the termination as of 12/31 was legitimate, you're entitled to get a refund of the premiums that you paid for Jan, Feb, Mar and Apr.)

The elimination of the prescription coverage could be legit. The employer is only obligated to provide you with what is provided to active employees, and if prescription coverage was cancelled altogether, it would come off the COBRA package as well.

If you don't get anywhere with the insurer or the "COBRA company", then consult an attorney there in ATL.