You can get them on this page while the offer lasts
You get the full collection of:
Analog Efex Pro. A filter that recreates a traditional film and lenses look
Color Efex Pro. A comprehensive set of filters for color correction, retouching, and creative effects.
Silver Efex Pro. One of the best colour to black and white conversion filters.
Viveza. Helps you selectively adjust the tone of your images.
HDR Efex Pro. An excellent tool that helps you create HDR (High Dynamic Range) images in Photoshop.
Sharpener Pro. An advanced filter that helps you fine tune the sharpening of your images.
Dfine. A filter that removes noise from your images. Like the other filters you can apply the effect locally or over the entire image.
While it's great that these professional grade filters are now free I wonder if it means that Google are going to stop developing them and leave them to rot. It won't be the first time they've bought out a company, used parts of their technology that they like and dumped the rest.