Anyone in your connections can view your presentations and if they have SlideShare installed they will be able to comment on your presentations too. If you have added SlideShare to your profile page, people that visit your profile page on LinkedIn (when logged in) will be able to see your presentations.

You can invite your connections to add SlideShare to LinkedIn if you would like to see more presentations in your connections, but they don't need to have SlideShare added to view your presentations. You can also share your presentations on Twitter by clicking on the "Twitter this presentation" link.