In August 2010, Google released a feature to enable Google Place business owners to respond to reviews in their Google Place pages.
If you read the ongoing Google Places Help thread, you will see that Google fixed it a couple times, but every time they fix it, people complain that it still doesn't work.
A couple days after Stephan from Google said the issue was fixed, again - people came in to say it still doesn't work for them.
I know how bugs can be and I know Google wants to fix it. So if you are still having issues, explain to Google how they can reproduce those errors so Google can fix this once and for all.
Forum discussion at Google Places Help.