I promised VTT hinted Merriweather some time ago now. I need to explain why you don’t have them, what is happening now, and what to expect next.
The primary reason for the delay was the formation of a new company to provide Google Web Fonts with many many more fonts than Merriweather. These new fonts will be in a wide range of styles and are almost all display types. The name of the company is Sorkin Type Co. I have been able to show some early proofs of these types to people I respect and the reactions has been very positive. The process of arranging for all of that is now complete and I have been back to work on Merriweather.
I am doing the final testing and adjusting of not just of Merriweather Bold now but also the Heavy. This means that quite soon there will be 4 styles – a Light, Regular, Bold and Heavy. The first 3 weights share widths and will take up the same amount of space. The heavy has its own set of of widths.
When these are done I am expecting to quickly produce a matching set of Merriweather San Serif fonts in the same 4 weights for a total of 8.
After this you can expect italics for both serif and sans designs.