I noticed the following item in the Debian Weekly News:
Standard C++ Library Modification. Matthias Klose announced that
the memory allocator in the standard C++ library will be changed which
requires several packages to be rebuilt for which he has appended a
list. The library will be updated by new versions of the gcc-3.4
and gcc-4.0 packages. Maintainers may have to rename the
binary packages to reflect the new dependency.