1. A system for using multiple speech recognizers, the system comprising: an allocation determination mechanism to determine an allocation of speech recognition tasks among multiple speech recognizers based on a complexity of a speech, wherein the multiple speech recognizers include a mobile-based speech recognizer on a mobile device and a server-based speech recognizer on a server, wherein said allocation determination mechanism is to use a threshold set on a vocabulary size to determine the complexity level of the speech, a task allocation mechanism to allocate the speech recognition tasks to both the mobile-device-based speech recognizer and the server-based speech recognizer based on a determination by the allocation determination mechanism; and a combination mechanism to receive results from the multiple speech recognizers and combine the results into a single result, wherein the results from each of the multiple speech recognizers include recognized words and a confidence score for each of the recognized words, and wherein, to combine the results, the combination mechanism is to compare the results from the multiple speech recognizers on a word-to-word basis and select a word from one of the multiple speech recognizers as a recognized word for the single result based on the confidence score of that word.
8. The system of claim 1 , wherein each of recognized words in the results from the multiple speech recognizers further includes a weighting factor for the word, and wherein the combination mechanism is further to select a word from one of the multiple speech recognizers as a recognized word for the single result based on the weighting factor of that word.