Looks like an interesting service, but I don't think it will work for WeBWorK. WeBWorK is based on the mod_perl extension for the Apache web server, and I don't see that listed among the supported perl frameworks. WeBWorK version 3 (currently under development) is based on dancer, which is supported, so it may be possible to run WW3 there when it is released.
WeBWorK does work with Amazon EC2 Cloud Service (free for the first year). See this wiki post for details.