There are some really good products out there in the market at the moment…
Exinda – low cost, really good QOS / prioitisation and visibility. Falls short on acceleration (at the moment)
Riverbed – One of the key players in the acceleration market. Optimized algorithms for specific traffic.
Silver Peak – Relatively new, work well as a capture all acceleration device with QOS / prioritisation included.
One to watch – traffic squeezer. I’m always a fan of open source getting into new technologies, and this project seems to be a good start. Its still early days but I’m hopeful this will take off and become a contender in the future ahead.
A few of the above vendors actually have a virtual version of their appliance. Depending on your current investment in virtual infrastructure this may or may not be a good idea. I’m still a fan of dedicated hardware, but in some cases the redundancy provided by a virtual infrastructure can out way the potential performance gains.