I was reading Prokofy the other day and he hit upon another good idea for encouraging retention: create a panel which displays the multitude of things to do in Second Life.
So, for instance, you'd have a panel showing War Sims for Call of Duty-esque games, and a panel to some social clubs if you're into making friends, and a panel to a sandbox and building lessons if you're into making objects and so on. When you click on the panel you want, it spits out a landmark to a location relevant to that interest.
It allows the new user to sort themselves quickly and direct them to where they would go anyway if they followed the current path. Currently, they would land in an infohub, ask where so-and-so is, and then get a landmark. This system would cut the middleman. If all I want to do is rent a house and play with some pets because a Real Life friend hooked me on Sion Chickens, then it's not really necessary to hit an infohub and have to shout over a dozen or so other people asking where I can buy pets.
And again, you can have a feedback system. Ask: Did you feel you were directed correctly? Did you get where you wanted to go? Then you can adjust the landmarks that are sent in each 'mode'. This sim is treating newbies like dirt? Remove them from the Help Station.
This isn't exactly rocket science.