I tried to make really good and userfriendly registration and password retrieval e-mails. But I was not able to get the

In German language I need the first and last name to be polite. And I guess some other languages are similar.

please change:

function send_confirmation_email($user) (lib/moodlelib.php line 4919 in moodle 2.1.2)

it needs little change:
= $data->firstname = fullname($user); (please check, if the fullname function gives more than the firstname?? works like $user=firstname)
+ $data->lastname = $user->lastname; (this would not interfere with existing use of email settings)

see also : MDL-17808, Petr Skoda solved it like above explained.

I recommend to make all send_e-mail function consistent to allow user friendly e-mails.

Minimum e.g. as chrismas gift: add lastname where its missing, please. It makes live easier = less patches after update.