We are no longer accepting new sign-ups for Page Creator because we have shifted our focus to developing Google Sites, which offers many of the capabilities of Page Creator along with new features like site-level navigation, site-level headers, control over who can see and edit your site, and rich embeddings like calendars, videos, and Google docs. If you are currently a Page Creator user, you can continue to use Page Creator and your pages will automatically be transitioned to Google Sites later this year.
It's not clear if Google will also move the files uploaded to Page Creator, so you can continue to use them. "For migrated sites we will automatically redirect your googlepages.com URL to the appropriate sites.google.com URL to ensure your visitors aren't lost due to the transition. In addition, we will be providing a means for you to download your site so that you can easily export it to other services if you choose to do so," explains Google.
Instead of having two overlapping services, Google decided to develop only one of them. "By concentrating our work on one product we hope to ultimately create a superior product than if we maintained the two products separately."
I'm not sure if Google Sites is a good replacement for Page Creator, since the interface is more complicated and there are many limitations: you can't add JavaScript code, embedded objects or iframes, it's more difficult to upload files and to setup a simple site.
{ via Google Blogoscoped }