Erik Tews with the help of two others published a new attack on WEP called: Breaking 104 bit WEP in less then 60 Seconds.
Like the older attacks on WEP this attack uses sniffed IVs in order to break/compute/crack the WEP key. The nice thing about this attack is that it only needs between 40.000 and 85.000 unique IVs (older attacks needed between 250.000 and 1.000.000 in order to succeed). This already reduces the overall attack time since one needs to capture less packages. But the attack also uses a new/other attack on RC4 which further improves the speed. The paper gives an average of 3 seconds on 1.7Ghz Pentium-M. The attack even works with 5000 keys.
Info and tool