GraphLab is an online platform which provides analytic capabilities to anyone with large data sets which can be modelled as graphs.  The tool can be used for recommendation systems (such as the recommendations provided by Netflix), customer segmentation (such as the segmentation done by P&G) and other diverse applications. The company is still in its early stages and just last year (May 2013) raised $6.75 million from Madrona Venture Group and NEA. 
Since the company is still in its early stages, it does not look like they have attempted to do any positioning or targetting to specific market segments. The potential market is essentially any company, since all companies collect some form of data they can extract knowledge from, however the advanced tools and techniques that GraphLab provides are probably better suited for companies with much larger data sets such as the Fortune 500.
In my opinion GraphLab can benefit significantly by focusing on a specific market vertical, such that their platform provides all of the capabilities relevant to that segment in an easy to use package. By doing this they can clearly communicate the value proposition to potential customers and build on early adopters by showcasing them as success stories. Once a market segment is making good progress, they can start expanding to other market segments. The shotgun approach that they currently appear to be taking is very tempting (due to the large potential market) but makes it harder to clearly communicate the value proposition and offer a compelling product. Focusing on a specific market segment also allows them to provide better on-boarding for customers with market specific tools, documentation and support which is challenging when the customers are in diverse market segments – basically on their own to figure out what the capabilities of the platform are and how to best utilize them.