I asked exactly the same question to support today. This was there response. We are currently working on a major evaluation of EPiServer regarding Web Accessibility. The tests include WCAG and ATAG and we are planning on releasing the results in a White Paper as soon as possible, probably within the next few weeks. As of today, the main focus has been on beeing able to produce accessible content to the client. We are aware that the edit and admininterfaces lacks good support for accesibility and this is something that we will have in mind when designing next genaration of EPiServer (ie EPiServer 5). You are also correct in the assumption that the edit and admin-interfaces only supports IE. Browser independance is also something that we will have in mind for the next generation version of EPiServer. Hope that helps

Great info. Thanks for sharing. Frank :)