Is the upgrade to 4.1 worth it? I currently have a jailbroken 3Gs iPhone running 4.01.

I've really used the jailbroken part, but it's good to know that I can tether my laptop to the phone should I ever need to.  

Having said that, is it worth it to upgrade the phone to 4.1 (which hasn't been jailbroken yet)?  Does it fix the sluggishness issues that were caused by the upgrade from iPhone OS 3.x to iOS 4.x?
There have been no reported issues with sluggishness on the iPhone 3GS.
The issues with sluggishness relate to the iPhone 3G. The update to iOS 4.1 resolves these issues.