I would STRONGLY recommend anyone who lends an item out to ask for an item of equal or greater value as collateral. This way, if the person disappears or refuses to respond, you can sell their item to get yours back.
I'd also STRONGLY recommend establishing a time frame. If they need the item longer, then when the original date comes around, you can always change it, but that way you have a clear idea of how long is too long for them to have your item.
I've never borrowed another's item, but I had a friend who would borrow items of mine, and they'd always offer some collateral. They wanted to make it clear that they had no intention of taking advantage of me, and it made me feel very safe about the whole situation, so I'd recommend this even among friends.