With the introduction of node title as a translatable field some previous behaviors of Drupal should be analyzed.
First of all since node title is a field, it can be modified by contributed modules by hook_node_view() and hook_node_build_alter(); on the other hand with you will always need to specify which title version use: the source title (the title in the original language) or the title displayed in the current content language.
This situation may cause an inconsistency between the title version displayed at node view and the title version displayed by other modules/components, e.g. we might have the title properly translated at node view (the title value is fetched from $node->content['title']) and a wrong title in the breadcrumbs on comment preview (the title value is returned by node_get_title(), which is the equivalent of $node->title, i.e. the title in the original language).
The attached spreadsheet lists (hopefully) all the cases in which node_get_title() is used and what title version ought to be used IMO.
As you can see these are mainly administrative pages, watchdog, logs and messages, but not only.
We should primarily decide if a module should be able to alter the node title (which was not possible before, because only $node->content was alterable), then we should solve the problems related to the translatability of the title case by case.
|FAILED: [[SimpleTest]]: [MySQL] 18,586 pass(es), 1 fail(s), and 0 exception(es).|
|Invalid PHP syntax in node.tpl.php.|
|Failed on MySQL 5.0 InnoDB, with: 17,316 pass(es), 0 fail(s), and 348 exception(es).|
|Failed on MySQL 5.0 InnoDB, with: 17,317 pass(es), 0 fail(s), and 348 exception(es).|
|Failed on MySQL 5.0 InnoDB, with: 17,308 pass(es), 3 fail(s), and 424 exception(es).|