It's a pleasure to inform that VeriSign published recently the The Domain Name Industry Brief (September 2008) mentioning .PL domain as one of the fastes growing ccTLD regardless of the fact that domain market delicned in Q2 2008.
VeriSign says: "The number of new domain name registrations across all TLDs in the second quarter of 2008 was 11.7 million. This represented a decline of new registrations by 18 percent from a very strong first quarter and eight percent from second quarter 2007, driven largely by a decline in ccTLD growth. The number of new domain name registrations reflects seasonal slowing historically seen in the second quarter."
Despite this general slow down, "In addition to .au and .br, the overall ccTLD growth was also driven by double digit growth quarter over quarter for .ru (Russian Federation) and .pl (Poland)"
It's also important to remind that .PL was mentioned in previous VeriSign Industry Brief (June 2008): "few ccTLDs that experienced remarkable double digit growth quarter over quarter, including .pl (Poland), .cn, .es (Spain), .ru (Russian Federation) and .fr (France)."
VeriSign Q1 report can be dowloaded here.
VeriSign Q2 (recent) report can be dowloaded here.