is there any way besides holding the home button to get to the voice control on the iPhone 4 like an app button or anything?
IPhone – is there an app button for the voice control on an iPhone 4
applicationsiphonevoice-dictation
Related Solutions
The official answer is No.
As of iOS 4, there is a simple workaround, however. You can just add a podcast to a playlist and speak "Play playlist PlaylistName".
In Settings > General > Passcode Lock (Yeah, a weird place, but hey ho) you can limit the voice control to music options only, and turn off voice dialling. This doesn't disable the long press option, but it does mean that at worst it can annoy you rather than embarrass you...
Note that for Jailbroken devices, there seem to be a number of tweaks and hacks that will disable the function entirely. The following links are from a brief google, and I haven't tested them as I do not jailbreak but they look promising:
Best Answer
The (very) short answer is "No there isn't".