I must disagree.
I've got two Powermates, silver and black . I got both of them in July/June. One I bought from Thinkgeek and the other I got for finding a bug in their drivers (Iíve reported on it here before).
Both work fine when plugged in from boot, with and without a hub.
During POST, both will pulse twice and then go dark for the rest of boot. Once NTLDR is finished and XP is loading, The powermates LED goes on and stays on.
It works fine once the desktop comes up.
The issue here is Drivers. Griffin is indeed a company that makes hardware for Macs. As such, their windows drivers and software leave much to be desired (desires I've had since June).
If your drivers are not properly installed, stuff stops working, and it's very easy to not install them right. Each USB port you use it on you have to go in and manually install the drivers.
There are some hardware differences between the black and silver powermate, The PCB's are different, and I've also heard rumors that the black are less sensitive. I have not seen this myself, so I can only assume they had not checked to see what the sensitivity level was set at.
I really don't think that the Powermates have different firmware. The sticker was probably just there because they used a different batch of PROMís.
I have tested this on win2k and win XP pro with identical results. I have not tried with win98 (No 98 box to try it on).
Also, There was no need to state all that in so many posts, Just edit your previous ones if you have to add something.