I just recently jailbroke my itouch and everything was working fine. I have only downloaded three themes(Glasklart, Silent Hill, My Other Car is Also a Porsche), a fontswap application (Team Fortress 2), and a new battery design (Aperture battery). However, and this doesn't occur 100% of the time, but occasionally the home button seems to be unresponsive and takes around 10 presses before it recognizes it. I at first thought it was an application I had downloaded or perhaps a cydget I got, but I have removed all of the applications and the situation has not changed. The listed applications/themes are currently on the itouch again. I have not tried to restore/re-jailbreak.
It's not a major problem, but it is a bit irritating that it is not as smooth as it was before I jailbroke it. I'm not sure if this is common or not, but I am looking for a remedy to the issue.
If you really want to determine if it's a hardware or software issue then you should do a restore via iTunes. If all is good then something you installed corrupted the device. If it's still not functioning correctly then you next move is taking it to a genius bar for exchange. Keep in mind that if they decide to give you a ipt 3g then you will be stuck with a tethered jb. Good luck.