What do you mean it's "gone"? First of all you should always use the restore button.. NEVER the upgrade button as you lose about 500MB of space on your iphone forever until you restore... second the update button causes all kinds of issues with hidden apps and categories. I recommend you restore and jailbreak from scratch.
Okay, well that explains why I went from 7gb to 6.5gb of free space. Though when I did the jailbreak, I had to use restore anyway, so I don't know where that space went.
I figured out where the folders went, I just had to make some.
Haven't figured out multitasking just yet. I tried the double tap of the home button, and it did switch to resent apps, so I guess it works.
I just puzzled me a bit as it felt different than before. It seemed to have been running faster just after the jailbreak than after the 'restore as previous iPhone.'-which the restore I am talking about. Not an OS restore.