The last city to ressurect tramways has been Buenos Aires, Argentina (with an Alstom Citadis model in the picture). Tramways (streetcars in North America) have made a huge comeback in recent years. During the '50s, trams was replaced by diesel buses, which offered greater flexibility at that moment and were considered far superior. However, buses have a huge drawback called tailpipe emissions and metropolitan areas, which are always more congested, were in the search of better solutions.
So the new tramways arrived. Silent, more flexible, more ecological (including regenerative braking that sends back energy to the power grid), sleek, faster (usually with segregated throughways) with low floors suitable for handicapped people... Cities have then put the tracks back on the streets or renewed the remaining tram lines with a general sense of success.
Of course, criticism has been heard as well. Motorists had trouble to adapt to the new trams, with reported accidents during the first days of operation. Trams are also perceived as a "poor-mans" subway (metro) because of the lower capacity and speed than subways, and the visual impact. And there's always the question of the origin of that clean electricity.
[Source: El Pais, Wikipedia]