Yes. Dynamically or statically it doesn't matter. The LGPL (originally called the Library General Public License but now called Lesser General Public License) may be dynamically linked to non-GPL programs but not statically.
The standard C library in Linux is GNU libc. It is LGPL so proprietary programs can and do link against it dynamically. Libreadline is GPL and may not be used by anything other than GPL programs.
Further, patches involving 10 or fewer lines of code fall beneath the threshold of carrying their own copyright. Patches involving more than 10 lines of code are copyright the author unless assigned otherwise.
GPL'ed code is copyrighted, however, in order to make any contribution (under the above guidelines) to code that Stallman considers `GNU', you have to sign a formal copyright assignment to the FSF. I don't believe this will stand up in court if it is actually tested. I signed a blanket copyright assignment covering past and future changes to Emacs and XEmacs to the FSF in return for compensation of $1 and I still haven't received my $1.