Simply: No.

Less blunt: Not unless you change the code. We don't allow HTML in there, either, because the title is used as part of the permalink. Adding special characters or markup would require some way to back-track the pretty URL to an entry, and something to replace the characters in ...

hi,

english:
is it somehow possible to create a linebreak within the headline of an entry?
thx in advance for your help,

deutsch:
kann ich irgendwie einen zeilenumbruch in einer eintragsüberschrift erzwingen?
vielen dank im voraus für eure hilfe,

kilowahn