If you start up GT5 today you will be prompted to download patch 1.02. The 133mb patch adds as promised weight and power restrictions to online racing. No mention in the news section of GT5 what other changes are made.
I got it first thing this morning, and I don't see any obvious changes. As well as the restrictions you mentioned, I read somewhere they were doing something with the interface too, though that wasn't official. I must admit that it annoys me when devs don't tell us exactly what their patches are doing.