HP Polyserve is not just a Cluster software but it does provide a well consolidation feature where 15-20 SQL server instances can be well managed on a well configured server (number of instances can be more on one server but this is just a well estimated guess as per my experience). However, getting the support for HP Polyserve is not so easy and not sure the future of product as I had heard that HP is working on newer similar product and the Polyserve is almost to an end of life!

You can get more information on HP's site.

Thanks,

Vikas