We were talking a bit on Ventrilo pre-match last night about PunkBuster hardware bans and how it seemed a bit harsh. Here's a statement from EvenBalance (posted on TWL's main page) about how the hardware bans work:

When players raise a violation that corresponds to hacking or interfering with PunkBuster's normal operation, we now (in addition to Global PB GUID bans) are Globally banning the new Hardware GUIDs across all games supported by PunkBuster (including games supported in the future). So punks who are determined to cheat so badly on PB-enabled servers that they try to hack PunkBuster may now need a new computer in addition to a new cdkey in order to return to PunkBuster servers.
So the only way you'll get a hardware ban is if you're a total smacktard who not only cheats but tries to hack PB as well. Significantly less harsh.