Are gondolas a real means of transportation in Venice or is it only a tourist attraction

A gondola is a traditional Venetian rowing boat. Gondolas were for centuries the chief means of transportation within Venice and still have a role in public transport, serving as traghetti (ferries) over major canals.

http://en.wikipedia.org/wiki/Gondola

Here are the seven public still in work:

Most traghetti have been operated by the same families for generations. As recently as the 1950s, there were some 30 of these gondola ferry routes; today, there are seven:

• 
  Fondamente S. Lucia (in front of the railroad station) - Fondamenta San Simeón Piccolo
• 
  San Marcuola - Fóndaco dei Turchi (by the Natural History Museum)
• 
  Santa Sofia (near Ca' D'Oro) - Pescaria (fish market)
• 
  Riva del Carbòn - Fondamente del Vin
• 
  Sant' Angelo - San Tomà
• 
  San Samuele - Ca' Rezzónico
• 
  Campo del Traghetto - Calle Lanza (near the Salute Church)

http://europeforvisitors.com/venice/articles/traghetto.htm 

Here is an article you should read before taking a gondola:

http://europeforvisitors.com/venice/articles/gallivanting_by_gondola.htm

Gondolas are pure tourist attraction in Venice, and a very expensive one. But there are two types of motor boats that are used for real transportation - one type is like a bus, and the other is like a taxi. 

Yes - little motor boats for transportation of stuff by the natives

Gondolas with traditional Gondoliers are strictly for the tourists - and mostly for the wealthy ones at that !