I found something new this year, looking for informations on their website:
it looks like they have now some 3G (WCDMA) coverage, and (very expensive) data plans:
ETC Home
but the GPRS tariffs are more affordable, here is the plan for those and GSM calls:
ETC Home
anyway it looks like you cannot access 3G and GPRS with foreign SIMs roaming there (at least no data is allowed for Italian carriers that have roaming agreements with them)