sclitheroe, I don't have any memory issues with the multitasking... nothing crashes. Even with the memory down to 20 MB or so the phone doesn't lag any more than it does with 100+ free, so I stopped paying attention to it. All I really want to run is TweetDeck, Facebook, Safari and CBC Radio without it being a pain in the ass to switch between them.
Russic, not sure if you were doing this or not but ideally you need to use an app in combination with Backgrounder to multitask properly; I use Circuitous to control it, looks like this but I moved that pop-up dock to the bottom like iOS4...
Which looks like iOS4 multitasking yes, but what makes it better is the control of it using Activator. Swipe gestures from the corner of the screen to cycle/close apps, double tap status bar to cycle, double press home button to cycle apps, etc. etc, however you want to control it. Even better, control over specific apps and how they multitask (if at all), instead of having to cycle through every single app you've opened in iOS4's dock. Hate how they moved the iPod controls in there as well.
Here is ProSwitcher, brings up a preview of the app to which you're switching, Palm Pre still. Uses a bit of battery so I ditched it, but a nice touch.
Also forgot to mention SBSettings... a quick swipe/double tap (again, up to you) over the status bar brings up all your toggles. Love this because I'm always tweaking brightness and killing wi-fi/location/bluetooth when I don't need them to save battery; this makes it a ~5 second affair to do all of that. Also a quick toggle for 3G Unrestrictor to allow YouTube HQ over 3G, etc. The switch isn't showing up for some reason but Rotation kills the accelerometer like it does in iOS4.
SBSettings alone is worth jailbreaking for. Last but not least...
...choice is yours if you want to pay $10 for the app or not, but no additional cost beyond that. Enough said.