There's no shortage of grocery lists apps for the iPhone and iPad. One of the more popular apps is the free Grocery iQ, which has added speech recognition from Nuance in an update available today. That addition hoists Grocery iQ a bit above the average list-maker.
You can add items to your shopping list by typing, scanning barcodes, and now by simply talking to your iPhone. The app lets you access coupons (the app is provided by Coupons.com) and also find nearby grocery stores. The app database accesses millions of items, so you're unlikely to be stuck with an item that is unknown.
When you first start up the app your list is already populated, and I saw some ads from Hormel with accompanying coupons. I didn't find it a distraction, but I would have preferred to start with an empty list, rather than one partly filled out for me. The speech recognition was excellent, and I tested it with some obscure locally sold brands and all were identified quickly, which was an impressive feat. It has been suggested, but not confirmed, that the Nuance speech recognition engine is the same that powers Siri on the iPhone 4S.
While this new version has added speech and multi-barcode scanning, it has also taken away certain features (favorite lists for a particular store and aisle layout, for example) and rankled some users.
Still, I found the app very useful, and the addition of highly-accurate speech recognition is a real time saver. If you're not married to your current grocery list app, I'd take a look at Grocery iQ. It's a universal app, and requires iOS 4.2.1 or greater.