Yes.It is true that Gravatar is sold and Automattic acquires Gravatar.I do not know how much Automattic bought is but the most important thing is now Gravatar is under Automattic.There is features after this and this will be more benefits to their user.

• They are transferred the Rails application and most of the avatar serving to WordPress.com infrastructure and servers.
• More than three times as fast, and works every time.
• Make all of the Premium features free, and refund anyone who bought them in the last 60 days.
• Bring the bigger sizes (128px)
• Allow Gravatar profile pages with Microformat support for things like XFN rel=”me” and hCard.
• Develop a new API that has cleaner URLs and allows Gravatars to be addressed by things like URL in addition to (or instead of) email addresses.
• Rewrite the application itself (site.gravatar.com) to fit directly into our WordPress.com grid, for internet-scale performance and reliability.
• From Gravatar, integrate them into all WordPress.com templates and bring features like multiple avatars over.

Well before this we already got benefits from Feedburner that acquired by Google and now we will get more benefits when Automattic acquires Gravatar.It is time to implement Gravatar on my blog.