We also keep a presence in LinkedIn, Facebook, and Twitter. One very useful feature is crosslinking across the three and your website blog and your press release service - post to one and a short version shows up on the others. Blogs are incredibly good for SEO.
I would love to see some landscape lighting pros make better use of Twitter. Twitter can create celebrity if someone makes frequent interesting posts. We all live in our own reality shows but few people get to see them. Twitter is a way to share our thoughts and experiences in a real and timely way. Even if one can only post before work, during lunch and after work - that could be interesting. Imagine posting things you might share with your buds at the bar - make it real. Could be big! Takes courage.