Today, someone came across this blog searching for "visa waiver latvia estonia usa 2008". They were probably looking for this story but the story is not so good for Latvia. Estonia (along with Greece and Czech Republic) was added to US visa waiver program. Latvia (and 7 other EU countries from CEE) was not.
Still, it's a good story. Trends in Latvia often mirror Estonia, with one or two years delay. Canada stopped requiring entry visas from Estonians in September 2006 and from Latvians, one year later. So, visa-fre travel to US in 2009 and 2010?