Some interesting questions and answers from the Vodafone UK's FAQ about its Dell Mini 9 netbook here, which highlights various of the upsides and downsides of this model. Will be interesting to see how these (and T's and C's) vary between operators once this approach has evolved a bit more.
Some pertinent ones:
"Can I run Microsoft Office?" - essentially, no, it doesn't have a CD drive or the processor clout to give good performance.
" If I switch network operator, can I still use my Dell netbook? : After your agreement with Vodafone has ended you can use the netbook with another operator. You will need a USB modem from your new operator and will need to re-configure the settings to be able to access their network."
"Can I upgrade the Dell netbook, e.g. larger hard drive, faster processor, more memory?" - No.