For the Dutch impaired [and in short]: The belgian authorities warn against a new XTC-pill with a question mark as logo. They are said to contain a very high dose of MDMA.
Did a search on pillreports and some results came out, but not really in Europe. However, as traffic is fast, it may well be that these have indeed surfaced and if so, it might be a good idea to read what others have to say about the effects. Note that not all reports are of the same quality, but it gives you an idea of what MIGHT be in a pill, and also forewarn you for really bunk pills.
Keep it safe,