That plan works in Italy only. When you are here in Italy I suggest a prepaid card of the UMTS operator 3. With 9 euros per month you can get up to 50MB per day, which is not bad at all. 3 has the widest 3G HSDPA coverage in Italy. And it's also the most reliable 3G network here. They also have a 5GB/month plan too...
Another option is the Mega15000 offer by Wind: you have 5GB/month in Italy or 50MB outside of Italy, which is not much, but could help. All for 30 euros per month. Unfortunately Wind has almost no HSDPA coverage and 3G only in bigger towns. They have anyway several 3G roaming agreements outside of Italy (I just used it once again in Germany on several networks).
AFAIK in Greece there is no similar offer, while in Switzerland there's surely something and in Austria maybe there could be some offer by 3 Austria, but their coverage is quite ridiculous... surely there's some offer with A1 Mobilkom but they are generally very expensive.
I suggest you to buy ad PC card on eBay which supports UMTS/HSDPA on the European frequency (2GHz). I fear the card sold by Cingular works only on the American 3G frequency (1.9GHz) and in Europe is useable only on GSM/GPRS/EDGE.
Anyway in several places you can find "open" Wifi networks...
