I found some information on lithium phosphate (seems to be more commonly called "Li-Ion Phosphate" or "Lithium Iron Phosphate", with an abbreviation of "LiFePO4").
It looks like there's only one company really making these batteries; Valence Technologies, Inc. (
www.valence.com ). Their Saphion batteries are cylindrical and seem like they would be the likely first candidate for R/C use, but they don't have a very high current rating as an individual cell; 11A with a 27A burst. They are 10C cells, but it looks like they are only made as 1100mah, which would mean needing to make them parallel.
Here are a couple links at Valence which are very promising.
http://www.valence.com/faq.asp?topic=phosphate
http://www.valence.com/pdffiles/IFR18650p.pdf
It looks like the batteries simply can't catch fire from abuse since the materials used to make them are non-combustible. This is even safer than nicd and nimh.
The only places I can see these cells currently in use are the Segway human transporter (scooter thingy) and a couple car companies working with them for hybrids. I can't even find them for sale on the web. Probably have to contact Valence directly to inquire.
A Google search for "lithium iron phosphate batteries" will give you a lot of articles praising the technology and some good information.