Just wanted to add to the info on Ibo Island and Pemba as I just got back from a trip there (April 09).
Pemba is not a great place to spend too much time, it is the gateway to the Quirimbas Archipelago so likely you'd need to stay a night or two to arrange travel to the islands. Firstly I stayed at Peter's place. Wouldn't recommend this place, they don't do food and for US $55 its over-priced. They had one small single room and the bathroom was awfully small. You could sit on the toilet and have a shower if you wanted- it was that small. The owners weren't that helpful and kind of leave you to your own devices.
After returning from Ibo I opted to stay at Residence Emilio Regina which was next door to Peter's place also at Wimbi Beach. This was much better with larger rooms, optional breakfast and more helpful reception staff. This was slightly more expensive at US $70 p/night but I was happy to pay extra for a better place.
On Ibo Island I stayed at Miti Miriwi (spelling?!). The translation is Two Trees guesthouse. The place is lovely and newly converted. Rooms are large. It is also US $55. However the service has a lot to be desired. They were ill equipped for my arrival, having no drinks, water or milk available. I had to wait 2.5 hours for breakfast the first day because of no milk and dinners which you can opt to have there if you like were very slow also, having to wait several hours. The wife of one of the owners is also very strange and unprofessional towards guests and you feel like you've invaded their home and are a bother. She prepares the meals but often makes you feel like she doesn't want to. She also started a domestic with her husband at the bar dragging me into by saying her husband was flirting with me, by just chatting to me. I felt very awkward after that and I wanted to leave.
Other points of feedback, there was no servicing of my room for the 3 days, there meal, drink and day trip prices are not very transparent, so ask as you get things so you don't get a nasty shock at the end.
They do organise day trips and I did the walk to Quirimbas Island at low tide which was good.
I did manage to do lunch at Ibo Island Lodge and that place is lovely and food is great, so if you have the money stay there. Miti is ok, but I would opt to not spend too much time at the bar (roots bar), or eat there next time.
Hope that helps with travel to Ibo