I bought a Moshi Mini DisplayPort to HDMI adapter about 8 months ago. It was working fine, then I started to have to move the adapter to get a picture (this was so frustrating as it took 2-5 min) and after a month or so it suddenly stopped working. I thought at first it was the HDMI cable but after trying with several different cables that I then realized that the problem is with the Moshi adapter. When I did a search, I found out that a lot of other users have had the same issue. I'm currently looking into buying the Belkin Mini DisplayPort to HDMI adapter but not before knowing if it's any good.
http://store.apple.com/ae/product/HA826ZM/A/belkin-mini-displayport-to-hdtv-cable-4m?fnode=51
http://store.apple.com/ae/product/HA826ZM/A/belkin-mini-displayport-to-hdtv-cable-4m?fnode=51