Nope, at least not for some time. I lost faith in the JB process when things went awry with updates to several apps. The complexity is simply too much work for the benefit given most functionality I want is in OS4.
I originally JB for GVMobile, 3G Unrestrict (for Skype), used folders and multitasking and a few eye-candy apps. With the web Google Voice app (agreeably not as good as GVMobile, but good enough), and base OS addressing the others, I don't see a compelling reason to go through the headaches again, yet.
Don't get me wrong, JB is great for many for a lot of reasons. JB community offers Apple PMs a broad user base to cull for future OS features. I suspect they toy with closing exploit holes so devs get the impression they are trying to eliminate the options. But at the same time, the great ideas of the dev community rise to the surface and they can assess what features they need to please the envelope pushers and maintain a loyal base. Clearly, folders and multitasking were demonstrated as effective and popular by the JB community and rose to the top of the Apple list as a result.
Monitoring and implementing the popular JB features gives Apple yet another way to play cat and mouse with the JB community. For some time after 4.0, JB interest will wane and App Store will sell a greater % of the mobile apps. Eventually, the brilliant minds in the community will add must haves on top of the OS4 feature set and create renewed interest in JB for those willing to put up with the challenges for a few advanced features. I see this game going on as long as the OS remains restricted (presumably indefinite given Apple's propensity to maintain control).