While researching the UMTS stick to buy for our Acer Aspire One netbook, I stumbled across some postings about using the Vodafone UMTS stick with Linux (see here (german)).

That forum discussion contains a link to https://forge.betavine.net/projects/vodafonemobilec/ where you can find “Vodafone Mobile Connect Card driver for Linux is a GPRS/UMTS/HSDPA device manager written in Python, licensed under the GPL”. I am impressed and just ordered two of these sticks.