iSpot owners' service plans if they go through with this -- for all we know, they'll detect un-iPad-like amounts of usage and threaten to up your monthly fee -- but if you're the risky type and you've got an iSpot lying around, its pesky MAC filtering can be a thing of the past with just a tiny bit of effort. There's a blog out there that now has concise instructions posted for gaining root access on the hotspot and tweaking config files to obliterate the MAC filter and enable USB tethering (by default it'll only do WiFi), but if that's too much effort for you, another site -- cheekily named "iSpot instant jailbreak" -- just hooks you up with a binary that you can upload to the iSpot to take care of the filtering in one fell swoop. Again, proceed with caution, because it's anyone's guess how Clear is going to take all this.
Update: We've pulled the iSpot instant jailbreak link after hearing reports that it might be doing more harm than good -- and there might even be some malicious intent involved because it apparently opens a backdoor that allows remote access to the admin console. Welcome to the seedy underbelly of device hacking, folks.
Update 2: The creator of the iSpot instant jailbreak just reached out to us know that the remote admin issue was "an error on [his] part" and that the latest version of the config file has it removed; we've re-added the link to it, but as always with these sorts of things, use caution here and be ready for potential flakiness.