I've been building links - making submissions of 20 or so every few days. Not a huge number but today I checked my leading keyword and see my site's completely gone. It's also been dropped for a few other top key phrases. It's still in the top spots for long tail terms and brand search. Should I be concerned that I've been penalised or ride out the storm? I've checked across several datacenters and around half have dropped it, half is the same. I can remove some links if this will reign it back in if this is the best action to take...
Where have you generally been posting? It might be that Google thinks you've posted in bad neighborhoods. Or it could be that the links have been dropped by their originals and therefore Google just doesn't think you're relevant anymore.
I guess it is just an effect of Google Dance or you are already sandboxed. Check your content and links. For sure there is something missing there.