¿Salir y volver a entrar después de solicitar un permiso de estancia mientras se espera con el recibo?

Ok, esta es la respuesta autorizada que estaba buscando:

Foreigners awaiting renewal of their residence permits can leave 
and re-enter Italy if they hold:
1. the receipt issued by Italian Post offices (Poste Italiane S.p.A) certifying the submission of the application for renewal of their residence  permit or EC residence permit for long-term residents;
2. the expired residence permit;
3. their passport or other equivalent travel document .

fuente está aquí

Esto se aplica a los que esperan el documento por primera vez:

The same facilitated procedure is granted to foreigners who have submitted their 
application for their first residence permits for employment, 
self-employment, or family reunification, provided that:
1. they leave and re-enter Italy through any Italian external border crossing point (cicular letter 11th March 2009);
2. they show their passport or other equivalent travel document, along with the entry visa specifying the reasons of their stay (employment, self-employment, or family reunification ) and the receipt issued by Italian Post offices (Poste Italiane S.p.A.);
3. they do not transit through other Schengen countries, as this is not allowed.