It seems that there is a implementation of rope in my /usr/include/c++/4.5.1/ext/rope (and ropeimpl.h). I compared it with SGI STL and the code seems to be pretty much the same codebase.
I'm not aware of its status or if its functional or not. Nor i am aware if this is super old stale code, or code in progress
in any case, i haven't found any references about how to use it (if functional). Do you know something i'm missing? are there usage examples i can use?
EDIT if you see the cvs history here, you'll see last activity was 4 months ago, which doesn't look like pretty active, but doesn't look abandoned either.
It's taken straight from the SGI code, and is still maintained (I changed it just the other day to fix a longstanding bug) but is only documented briefly with the deprecated extensions.