The Windows 7 team announced the timeline for the shutdown of general availability for Windows 7 Beta, which will occur in 3 phases over the next few weeks. You're encouraged to download and trial Windows 7 Beta soon...so don't miss out!
For more details, please read the recent blog post from Windows Team Blog.
In addition, my team is now planning for the next release of Microsoft Assessment and Planning Toolkit (MAP 4.0) that may include hardware and device compatibility assessment for Windows 7 Beta (and subsequently RTM). We will disclose the confirmed release plan on this blog or the Microsoft Assessment and Planning Toolkit Beta site as soon as possible.