There are a number of companies doing interesting things with zinc-air, but the one I know the most about is Electric Fuel (http://www.electric-fuel.com).  I've been using a lot of their figures from their electric city bus tests.

Power Air Corp. purchased a bunch of LLNL patents for refillable cells, but they don't seem to have a web site.  Here's a press release about them.

Hmm, I meant www.electric-fuel.com in my previous post.

All this being said, the company seems to be under stress financially.  The stock price is below 1$ on the NASDAQ, which means they are in danger of being delisted.  In addition, it seems that in their most recent quarter they posted a loss, which may explain why the stock is in the toilet.  Their revenues were up, but they had to writedown of some stuff in a division unrelated to the fuel-cell division.

more info here

I have worked for startups and small companies, so I am sympathetic to the position they are in, and I know what they are probably going through.  Hopefully they will pull through it all.