I noticed that uploaded textures now get resized - that is, shrunk to roughly a quarter of the original size. I had a vendor texture with text that was pretty much optimized for the used font size (a single letter only 14 pixels high). After uploading, the text was blurred and not readable anymore (yes, I did wait until the texture was completely loaded).
I did cut out a quarter of the texture, thinking there may be a size limit now and wanting to do that vendor display in 4 tiles. The same effect. I ended up doubling the size in Photoshop, so the text was readable again (alas, with a great quality loss due to the interpolation in Photoshop and shrinking done by SL. But its still looked much better than the optimized original before).
I can understand that large textures can be a problem and perhaps many players don't think much of file size and compression. I personally spend much effort on saving highly compressed progressive JPEG's of max. 500 KB. Do I need to compress them at all, or does the game compress them again now? As a shop owner I need my wares and displays to look as good as possible. What about clothing and skin textures? If I want a resolution of 900x900, do I need to save them in 1800x1800 now? I really need a way to avoid any quality loss and to be sure that what I see in Photoshop (and later in Ulead's JPEG Smart Saver) is the same I'll see in SL.