Halloween 2012
Do Italians celebrate Halloween?
A: No. 
The celebration of Halloween is gaining in interest and popularity here ...but still not celebrated at large like in the States.  Pumpkins are available -but not plentiful like in the US.  When I notice them, then I start looking and checking prices.  They range from $1.25/2lbs. - $2.06/2lbs. 
In the city (where we live) people live in secure apartment buildings ...meaning there is locked entry door to each building (like in Seinfeld).  You have to know someone, ring their "doorbell" and then be "buzzed" in.  This makes going directly to peoples doors difficult ...thus making trick-or-treating hard too.
So, in short, they like the idea and small pockets of folks throw a party or let their kids dress up.  By in large, there is nothing happening here tonight.

Now, tomorrow is a celebrated holiday for Italians, All Saints Day with the following day, Day of the Dead.  It resembles our memorial day to visit loved-ones grave sites -but from a religious perspective.  November 1st celebrates the saints and November 2nd is to actually honor the dead.

Here is a list of recognized/celebrated holidays taken from about.com


Italian Holidays, Festivals, Feast Days
Below is a list of the Italian national holidays plus feast days for some of the major Italian cities and a representative sample of festivals:
January
1: Capodanno (New Year's Day)
6: Epifania/La Befana (Epiphany)
7: Giornata Nazionale della Bandiera (Flag Day)—celebrated principally in Reggio nell'Emilia
February
3: San Biagio (patron saint of Doues)
9: San Rinaldo (patron saint of Nocera Umbra)
14: Festa degli Innamorati (San Valentino)
Movable: Martedì Grasso (Mardi Gras / Fat Tuesday)—part of Carnevale
Movable: Mercoledì di Ceneri (Ash Wednesday)
March
8: La Festa della Donna
16: San Ilario and San Taziano (patron saints of Gorizia)
19: Festa del Papà (San Giuseppe)
19: San Proietto (patron saint of Randazzo)
Movable (can also occur in April): Domenica delle Palme (Palm Sunday)
Movable (can also occur in April): Venerdì Santo (Good Friday)
Movable (can also occur in April): Pasqua (Easter Sunday)
Monday after Easter (can also occur in April): Pasquetta, Lunedì di Pasqua (Easter Monday)
April
1: Pesce d'Aprile (April Fool's Day)
25: Festa della Liberazione (Liberation Day)
25: San Marco (patron saint of Venezia)
May
1: Festa del Lavoro (May Day)
June
2: Festa della Repubblica (Republic Day)
24: San Giovanni Battista (patron saint of Firenze)
29: San Pietro and San Paolo (patron saints of Roma)
July
10: San Paterniano (patron saint of Grottammare)
15: Santa Rosalia (patron saint of Palermo)
August
2: San Alessio (patron saint of Sant'Alessio in Aspromonte)
15: Ferragosto / Assunzione (Day of the Assumption)
September
19: San Gennaro (patron saint of Napoli)
22: San Maurizio (patron saint of Calasetta)
October
4: San Petronio (patron saint of Bologna)
November
1: Ognissanti (All Saints Day)
2: Il Giorno dei Morti (Day of the Dead)
3: San Giusto (patron saint of Trieste)
11: San Martino (patron saint of Foiano della Chiana)
December
6: San Nicola (patron saint of Bari)
7: Sant'Ambrogio (patron saint of Milano)
8: Immacolata Concezione (Immaculate Conception)
25: Natale (Christmas)
26: Santo Stefano (St. Stephen's Day)
31: San Silvestro (St. Silvester's Day)