"Why is my site not ranking anymore"
A quick look at their sites backlink profile quickly reveals a big spam fest of low quality web directories, blog comments, social bookmarking using primarly their main target keywords as anchor text.
Clearly a Penguin issue in at least 9 out of 10 cases so perhaps someone can write a sticky post that addresses the several Google updates and the characteristics that match with these updates.
Real quickly summarized:
- Panda (thin / low quality pages)
- Penguin (spammy / low quality links)