Might AML regulations have to be applied to unofficial currencies sites in EU? Is there any AML regulation in EU countries which might have to be applied to unofficial currencies, such as Bitcoins?

I guess usually they only apply to state-backed currencies, but since Bitcoins can be easily exchanged for EUR, there might be some (poorly written?) law which might extend to any site allowing users to trade it, and not only to the exchanges (as it would be logic to do, instead).
In the EU AML regulations do not apply to currencies, they apply to financially registered entities and a couple of other ones.

The entities required to ensure AML-compliance are : 


Banks,
Payment Service Providers,
Latin notaries (think about laundering money through real-estate transactions for example)
Licensed currency exchangers,
etc.


Legally compliant Bitcoin exchanges are not subject to AML regulations directly, since as of today, none of them is a registered PSP or bank. But, if they partner with such an entity they can get a delegation to perform AML-related duties such as KYC, under the legal responsibility of the delegator entity.