Having had an Iphone 3GS for a short time, i quickly got used to the ability to lock the handset using the button along the top and then it locking the phone. With an Iphone in order to gain access to the phone upon unlock the user would input a pin, which for security reasons is a huge advantage. I am at College, and frequently people want to have a look at the Latest Nokia Handset, on a number of occasions i have had my friends unlock my phone (without any security) and then go into my Facebook Profile page and post inappropriate comments.
I rang up Nokia Care and spoke to a guy who told me that this feature wasn't possible on the Nokia N8, we had a discussion about it and both agreed that this feature would be extremely useful to anyone using/wanting to use this particular device.
Posting this here to make the developers away of this floor in software design, and make a surgestion for this to be implemented in the next software update.