We don't have a formal system for that but we do announce customer early request betas. Sometimes they are invite only, other times we open them more broadly. In those cases where it is more broad it's usually featured on our homepage and then it's on a first come, first serve basis in terms of getting access and limited by the number of invitations that we are accepting.

It's a bit of a fluid process as it depends on the type of service, product, feature, we are rolling out.

Any chance I can get in on the beta for this? I've done the Load balancer and block storage beta? <username>@gmail.com

We will make sure to add you once the beta is available.