Does anyone know when ATI is planning to support the mobility radeon 4XXX series with thier driver?

I just got a new notebook with mobility 4650 and the performance under window$ is amazing, nearly on par with nvidia 9800gs even with ddr3 rather than gddr3. And this is on a budget notebook.

I really need linux on this notebook. Please if any one knows the release schedule or how often ATI upgrades thier drivers please tell me.