There are a bunch of commercial IOS librariers for speech recognition. The names I keep hearing are Nuance, iSpeech, and Yapme. Each offers cloud speech recognition (off the device) and a client library and SDK to build into your app.
Nuance seems to support Spanish - http://blog.dragonmobileapps.com/2011/01/mobile-app-developer-dragon-mobile-sdk.html
...you can speech-enable your app for including US and UK English,
European Spanish, European French, German, Italian and Japanese---with
even more languages on tap for 2011!
and now Nuance gives developers free access - http://www.masshightech.com/stories/2011/09/26/daily13-Nuance-tweaks-mobile-dev-program-with-free-access-to-Dragon.html
iSpeech is likely to support Spanish - http://www.ispeech.org/developers/iphone
iSpeech's Mobile SDKs support 27 TTS and ASR (defined grammar)
languages and 15 languages for free-form dictation voice recognition.
Yapme, sorry, I'm not sure - http://yapinc.com/speech-cloud.html