What do the symbols on the top of The Witcher 2's screen mean?

This looks like the symbol for the "Circle of Vigor" - a hexagon. It boosts your vitality regeneration for 5 minutes.

Likely you visited the Circle of Vigor in the forest outside Flotsam. The Circles all have unusual icons, but potion/oil effects typically look like the potion or oil that grants them.

I couldn't find any particular status screen that lists your effects and the symbol associated with them, sadly.

I realize this thread is long dead but if anyone gets here from a search, like I did:

You can see the names of active potions by Meditating and going to Drink Potions. Active potions will already be placed in the circles on the right and you can see their names by hovering your pointer over them (on the PC, don't know how this works on consoles).