Just a random observation which may not mean anything.
I was looking at the Market Cap values over at http://bitcoinwatch.com/
and doing some quick conversions. I found that EUR, PLN and GBP all worked out to a market cap of ~$14 million USD, and the PLN market cap is ~$17 million USD, while (at the time of the posting) the USD market cap is ~$16 million.
Is there a reason why the EUR, PLN and GBP exchange rates would tend to move in sync, separately from the USD rate, while the PLN exchange rate would tend to correspond more closely to USD? (I haven't confirmed that this is a trend yet and not just a coincidence.)