I just came up with the new starter shipping method -- no white powder involved.  

To create the “sourdough paper” I placed the sheet of Bounty paper towel on the plastic wrap film and poured the starter on the paper.  Then I dried it for a couple of days.  Bounty is good because it does not disintegrate easily in water.  The dried towel sheet is just a piece of paper and can be mailed easily without any special precautions in the normal mail envelope.

I tried restoring the starter from this form and it worked great.  I’ve placed a little piece of 

"sourdough paper" (2 x 2 inch) on the bottom of the cup and put  around 1.5 Tbs of purified water and 1 Tbs of flour, gently mixed it and covered with the plastic wrap.  On the second day I've added one more Tbs of water and 1 Tbs of flour.  By the end of the second day the starter got all bubbly and going strong (the texture and the smell are great).  I then discarded the paper and continued feeding as usual.

-Greg