I am unsure on a 3G, but I am currently using a 2G model and so far everything has been running smooth on it. So I suppose that it'll be the same for the 3G models.
i hate this jailbreak, it messed uo my ipod touch 2g on 4.0
right after Jailbreaking it with JailbreakMe i plugged it in to my computer and it went crazy it keeps on rebooting but it has crazy lines on the boot logo
Last night I upgraded to 4.0 on my jailbroken os3.1.3 ipt3g. Then I used jailbreakme.com just fine. Looked great except 11 pages was not quite enough for all my apps. But then I made the mistake of reinstalling AptBackup and using its restore function. My iPod went totally FUBAR. Most of the apps disappeared, and the iTunes memory usage bar showed all the green "App" data had all been converted to orange "Other" data. Yikes. So I had to do an iTunes restore and resync. But then the jailbreakme.com didn't work, dumping me back to Home. But this morning jailbreakme.com worked fine so maybe the server was just overloaded last night. Everything seems to be OK now; I am reinstalling Cydia apts one by one.
There is the known issue of the odd line of colorful pixels during boot, and the only issue I had was going to the jailbreakme.com. The jailbreak did not work, it just sat there. I found the modmyi mirror (jailbreakme.modmyi.com) and it worked perfectly. Thanks Comex!