David, I've been trying off and on today to find something for you that says the exclusion is still available to be used against gains on sales by estates or heirs, but I believe Lion is correct. This exclusion WAS available in 2010 only, and that's why the first linked document says "for sales after Dec 31, 2009". As far as I can find, in 2010 this was covered in IRC sec 121(d)(9) , that frustratingly now reads as something completely different.
If you look at this site, on page 4 of the right-hand column, in very fine print you'll see the amendments for 2010, the temporary additions of the words that would have extended the exclusion to estates and heirs. It's the last line of that first block in the amendments section. Hope that makes sense. Here's that site for the actual code:
http://www.gpo.gov/fdsys/pkg/USCODE-2011-title26/pdf/USCODE-2011-title26-subtitleA-chap1-subchapB-partIII-sec121.pdf