Hi Ila,
I think ethics is a really important point. I've done a number of interviews over Skype for research. There may be issues in how you prepare for these interviews as well as how you conduct them. For example, one case I had required obtaining phone or email contact details to organise the skype interview. Some students gave their mobile phone numbers so there are ethical issues in storing and using that personal information. Then there are ethical issues in how many times you contact them before they might see it as being a nuisance. I store all that information on record to protect everyone involved.
When you organise a skype interview I start by reading a statement setting out the purpose, duration and structure of the interview and I tell them how the data will be transcribed and stored and who will have access to it. I then provide them with contact details verbally and by email/SMS afterwards so they know who to contact if they have any issues over the way the research is being conducted.
Only once that's been done do I actually do the interview. After that its just like a phone call (plus or minus any pictures). There are a whole other set of ethical issues raised when you don't know the interviewee but I'll save that for another time maybe.
Nick
University of Glasgow