The first papers in JGR-Planets (Special Collection) - Mars Reconnaissance Orbiter Mission and Science Investigations should start appearing soon; in fact, I understand the Zurek and Smrekar paper will be published online tomorrow.

Note: A preprint (23 Mb PDF) of the McEwen et al. HiRISE paper has been available for quite some time.

I notice the one paper in the collection online thus far ("An overview of the Mars Reconnaissance Orbiter (MRO) science mission" by Richard W. Zurek and Suzanne E. Smrekar) contains a tidbit or two about the Ka-band equipment problem that was first mentioned
here. It briefly mentions (section 2.3.2) is that there was "a failure in the Ka-band exciter chain during aerobraking" and alludes also to "a possible impact on the nominal X-band telecom systems if the redundant paths were to be used". As a consequence the "operational demonstration of Ka-band" is "on hold". (The only consolation appears to be that during inflight testing during the cruise phase "the MRO Ka-band system set a new record for the rate of data return from deep space".)

Has any further information about this problem been released?

Public release? Not that I'm aware of.

The McEwen et al. HiRISE paper should be published online later today. And from what I understand, the Malin et al. CTX paper and the the Seu et al. SHARAD paper will be published online tomorrow.

From what I understand, the CRISM (Murchie et al.) and RS (Zuber et al.) papers should be published online next Tuesday.

The short answer is, the problem isn't a problem, so long as the spacecraft continues to operate in one mode. If the modes were switched, it could lead to problems with the spacecraft. That's about all I know myself about the problem, and it's been deemed by those who know that it's not a good idea to figure out what "problems with the spacecraft" are unless we have to, or are in super-extended mission.

The final paper of this series, McCleese et al., should be published online in a couple of hours.