The Polish style of nymphing is essentially the same as Czech Nymphing. In fact, the Czech method was derived from Polish Nymphing and the differences mostly arise in the way your leader is rigged.
As stated above, the Polish Nymphing technique is very similar to Czech Nymphing. The emphasis is on short casts and fishing close to your location. As with Czech Nymphing you will not be casting your fly line so much as you are casting your leader.
Fly rigging in Polish Nymphing is slightly different from Czech Nymphing. The heaviest fly, or the "anchor" is tied at the end of your leader with the lighter fly tied in further above it. When rigging your leader for Polish Nymphing, the tippet for the lighter fly is actually attatched by a loop between to blood knots tied into the main leader. This will allow the fly to move freely up and down the main leader between the two knots.
The only time the heavier fly is tied above the lighter fly is when fishing shallow runs or riffles. This allows both flies to get to the proper depth, and keep you from lifting them out of the water while leading with your rod.
As with Czech Nymphing, longer fly rods are preferred for Polish Nymphing. The longer the fly rod, the longer your reach and subsequently your drifts.
Czech Nymphs and other weighted flies are used, however woven nymphs are most closely associated with Polish Nymphing. As with the other European Nymphing techniques it is important to choose the proper weight to match the water you are fishing.
This page is just a simple introduction to European Nymphing techniques, if you are interested in learning more there are some good books and DVDs available.