On breakpoint XCode shows only aa array of vector members. So I can't view actual std::vector members, such as _M_impl. As I remember, there was this ability in XCode 3.x.
I need this data to set "Watch adress of ..." to check when it will be changed.
You can right-click in the xcode 4 variables window and select "Edit summary format...". This provides you with the same functionality as xcode 3.
That said, I still have yet to figure out how to inspect STL containers in xcode.