I think its very simple. Most new players that I have seen in the last few weeks at Adult Hub are looking for a few of the following things.
1 Help customizing their avatar (unpacking boxes and using their inventory, editing appearance, skins, shapes, AOs etc)
2 Making friends
3 The "so what do you guys actually do on SL?"question
4 Sex
And not necessarily in that order. I think If we are serious about retaining newcomers, the first point needs to be addressed, whether by LL or by giving some of your own time to helping newcomers. Some experienced players will ignore new players as it seems to be more trouble than its worth explaining how it all works.
Making friends is an important point, something we can all look at ourselves as being partly responsible for. We all judge the book by its cover to various degrees, I have found that you can find some good people behind those avatars if you take 5 minutes to just talk to them.
Activities are well covered by LL I feel, most new people can find something fun to do with a few clicks of a mouse. The helpers also do a good job here.
The forth point is self explanatory.