As a matter of policy, Jagex will not return your items if you should be unlucky enough to be "hacked." If some jerk is able to log into your char by various means, either keylogging, scamming, guessing your password, etc., then that's tough for you. Jagex customer service will help you get your account access back but they will not return your items.
"Our policy is to never return lost items to players that have been scammed." [Source: http://www.runescape.com/kbase/guid/scamming_prevention_guide]
Well, that is just so sweet of you, Jagex. Nice to know that you treat your customers like crap and do not offer any real support for your game. Although the previous link mentions only scamming, they also have the same policy for players who lost items due to someone gaining unauthorized access to their account.
You know, like years ago when Jagex was just a small struggling company, such things were quite forgiveable. But it has been nine years! In all this time, they never even made an effort to improve their customer service.
Meanwhile, in other games they actually have good customer service and mechanisms in place for returning items. World of Warcraft, in particuler, has huge subscriber numbers yet they still investigate every account if it is hacked and restore lost items.
"Luke: Blizzard were great with the issue. I went through both the in-game ticketing system and their online support site to get my items and account back under my control, and they responded quickly and professionally." [Source: http://www.techdigest.tv/2009/04/lost_and_naked.html]
*Note: I have never been "hacked." Nonetheless, I believe our players deserve better customer service than what we are getting.