Shopping cart optimization is one of the most often ignored area for small-to-mid sized ecommerce businesses.
This is a brilliant, simple solution - there are several "AI" cart abandon programs such as Upsellit.com, and other live-chat solutions, but Olark's inclusion of user data, cart value, and simple IM integration will make a big difference.
I'm 100% going to test this, and will report back about conversion results vs. other live chat or AI tools.