Well, I didn't say it would not be supported going forward, but it appears it isn't being enhanced beyond what you see in Access 2010. Here are a couple of links from more or less official Microsoft sources:

Create an Access project

Access Blog - ADP's and SQL Server 2008

There are a number of ways to create a "front-end" to SQL Server databases. They include the .NET approach, third-party tools such as Power Bulder, SharePoint, and others in addition to Access. We have substantial evidence that the fastest way to a working front-end is using Access - in fact the ratio of development effort for Access ranges from 1/3 to 1/5 depending on the specific needs and the alternative technology. That said, we also discovered that the linked table approach typically takes substantially less effort than using an ADP.

Bottom Line: If you already have an ADP project then don't throw it away unless you are looking at a complete redesign from the ground up. But do be aware of the limitiations with an ADP and the lack of support for some of the new data types introduced in SQL Server 2008 (and presumably in 2012).