It's not really a fully finished project yet, so not much. We shipped the AWS SDK for JS v3 with Smithy, the AWS SDK for Go v2 with Smithy, and just launched an alpha of the AWS SDK for Rust using Smithy. More are in the works. We're currently iterating on their code generators to make them easier to use outside the AWS SDKs. AWS SDKs are being built in a layered approach where there's a generic code generator that's really extensible, and then the AWS SDKs extend it to add AWS-specific stuff like regions and credential handling.

We're working to get projects like these to GA: https://github.com/awslabs/smithy-typescript, https://github.com/aws/smithy-go, and https://github.com/awslabs/smithy-rs. And we're also working on service code generation.