Thanks for the hints, I had the same problem, and installing Mesa-dri solved the problem. Although, this makes me a bit concerned about how will I be informed about "recommended" packages which are in fact required. As others mentioned, I'm also using --without-recommends, mainly because otherwise I'm offered with +600Mb of download of packages I'm not interested in (most of them are which I've deselected at the first installation from scratch). I hope a solution can be found for these kind of situations, so that the other TW users who don't read the mailing list aren't faced with non-working systems and questions like: "ooh, you didn't know you have to install X and Y package after today's dup to have a working system?!" :)
Thanks again, Best regards, Attila.