Google this morning dropped an update to their Popular Mobile iPhone App, including a feature that many people with iPod touches wanted:
Use the voice search function on iPod touch models that shipped with earphones that include the remote and microphone
Improved Voice Search stability
Fixes crashes on certain search queries such as searching "@"
Fixes a bug which gave you a hard time when you needed to paste something in the search field
Improved voice search completion detection
The iPod experience wouldn't necessarily be seamless. Users would need to carry around their earphones and whenever they needed to voice search they would have to plug them in and put them on.