The RST accompanying software, Intel Control Center and Intel Rapid Storage (programs), are definitely optional. They can be un-installed from the control panel.
There are other software from Intel that may be required like, Intel® Smart Response Technology, which may be required for mSATA connected SSDs to be used as a caching device. You'll see more of these, they are on new Ivy Bridge motherboards and laptops.
This is new hardware functionality and I'm not 100% sure if the software is required. I would assume there are other ways to turn on/off the required services.
All OEMs using Intel CPUs have the Intel RST drivers on their driver/support sites, some of them may include the programs.
Custom built systems will usually have the default Windows msachi driver. You will find Intel RST drivers listed on the motherboard driver/support site.
The RST drivers can also be used for non-RAID systems.