NASA, STEM and PBL meet the needs of 21st century education because the NASA piece adds interest for students.  When teaching Earth Science, my colleagues and I dedided to teach the Astronomy unit first, in order to grab the students' attention.  It works--students have a natural curiosity about space.
Then, when you have the students' attention, Web 2.0 tools are a natual fit to collaborate on a product to express their findings and communicate to their peers and the outside world, both parts of STEM and PBL.

I am excited that this class will be addressing the integration of Web 2.0 tools into the classroom, as that is what our school is trying to do this year.

• My first thought was to incorporate blog entries as homework to keep an ear to the ground as to who is understanding the content and who needs more assistance.
• I also have been experimenting with the use of shared folders in Dropbox with my colleagues at school. Not much activity yet. I have used Dropbox personally since February or so just as a replacement for a flash drive. (Dratted flash drives are never where you need them!) My next step with Dropbox is implementing useful shared folders for my classes. My students keep a running weather journal and I am thinking of having it as a spread sheet in Dropbox rather than a page in a notebook or a list on the board.
• Another thought is the use of personal electronic devices in class. Many students now have laptops, ipads or smartphones. A colleague has her students put them on the desk during class, and use them if/when appropriate as a tool. I will test those waters this year.
• I like to use some YouTube videos now, but would like to have my students do more video projects themselves.
• The Facebook idea is also intriguing. I know most of my students have Facebook pages, and would love to see/hear how others are incorporating it.