WPA is a more secure encryption system for wireless networks than the older WEP system, which was notoriously vulnerable. Now, Japanese researchers have devised an attack that cracks WPA networks using the Temporal Key Integrity Protocol (TKIP) algorithm quickly and easily. So far, WPA2 and WPA using AES are not vulnerable to the attack. On past form, it seems likely that those will eventually become vulnerable to rapid compromise, as well.
The broader point this demonstrates is how attacks always get better and never get worse. As such, the longer any particular system has been deployed, the less likely it is to be secure. Threat analysis needs to be ongoing, and accompanied by the patching and replacement of vulnerable systems. Both because of improving computer power and new mathematical developments, this is especially true when it comes to cryptography. As MC Frontalot explains (in a song that references rainbow tables), “you can’t hide secrets from the future with math.”