Will Siri be available on the iPod touch 4th Gen.?

No. Only the iPhone 4S.

no, siri is iphone 4s exclusive. heard it uses bigger ram n processor which i touch 4g do not have(cant confirm this though). but u could try dragon go! apps. its no where near siri but its the closest u could get to siri.

http://itunes.apple.com/us/app/dragon-go!/id442975871?mt=8

another option would be vlingo.

http://itunes.apple.com/us/app/vlingo-voice-app/id297214191?mt=8&ign-mpt=uo%3D2

I had SIRI on my iPod Touch 4G for six months. It worked fine until IOS-5 rendered it useless. Now it just says it can't find the network or network is slow.

Thanks for nothing, Apple. You have destroyed one of my favorite apps.

The Siri app you had was made by another company which no longer exists, so the back end servers that supported that app also no longer exist (it had nothing to do with iOS 5). Apple purchased their technology to use in other devices; they made no promises or even hints that they would continue to support that old app indefinitely.

This changes nothing. I repeat, thank for nothing, Apple. You have destroyed one of my favorite apps.