I've been having this problem, it's happened twice now.
My clothes disappear. I select different clothes to wear, and they get marked "worn" but I can't see them, sometimes people around me can see them but usually not. I switch avatars completely and it still doesn't work. For a short time there was one outfit that was working sometimes, but that one seems to be not working now too. This happened a few days ago too, and I deleted my SecondLife directory as well as ~/.secondlife and reinstalled and that seemed to help, this time that's not working. I've cleared my cache, rebaked textures, tried the test avatars in the client debug menu, everything I can think of.
The other thing that doesn't seem to be working (I think it's related since this also happened last time I was having clothes issues) is that the map doesn't show any texture. I can see people, and the icons for events and so forth, but the texture never loads.
The only other anomaly that I've noticed (and maybe this is normal, I didn't look when it had been working) is I seems to get a bunch of "WARNING: updateMeshTextures: invalid host for object:" messages on the console when I try to change outfits. It happens with the clothes in my inventory, and also with the test avatars in the client debug menu.
I also picked-up one of the freebee outfits on help island and tried putting that on and that didn't work either. I can change my skin, my shape, my hair, wear hats, but shirts and pants are a problem.