Dizon has been doing okay. One of the coaches commented that they had to rein him in, a bit. He's been doing a rookie blog for the Lions on their website.
Lions site (Check out Quotes and Press Box sections)
TWheat has been practicing against moss, and has been burned a couple of times by rm. But one report has it that he's been pretty impressive throughout camp. One of the commentaries/analysis from the 1st preseason game was that tight coverage by TWheat and another corner (might have been Hobbs) lead to a sack and fumble.
Patriots site (Latest News link seems to be the best)