In regards to libraries on the N900, the libraries we have on the N900 fit into several categories:
1.Libraries where we have a newer modern maintained version that is ABI compatible with the Fremantle version (e.g. libc) or that can be modified/forked to be ABI compatible (e.g. I suspect GTK2 fits in this category)
2.Libraries specific to Maemo where we can keep the same ABI (e.g. hildon or e.g. various closed-source libraries we are keeping around)
3.Libraries where the version on Maemo is obsolete and there is a newer maintained version and its possible to have both libraries side-by-side on the one system (e.g. openssl)
4.Libraries where the version on Maemo is obsolete and there is a newer maintained version and its not possible to have both libraries side-by-side on the one system. (this should not happen since the Linux convention is that you bump up the library version and create a new .so file any time you do something that breaks the ABI)
and 5.Libraries that can/will go away because they are no longer needed due to changes elsewhere