The short answer to which word to use is best summed up by this passage from Webster's New World Dictionary (Fourth Edition, 2003):
"The distinction between WILL...and SHALL...in expressing simple future time or determination, etc. is today virtually nonexistent in North American English; WILL and SHALL and their respective past tenses WOULD and SHOULD are usually interchangeable, with WILL (and WOULD) being the preferred form in all persons."
That's it in a nutshell. But it's worth mentioning that Webster's New World is the dictionary of choice for most newsrooms across America as well as some worldwide English-language news outlets. This dictionary reflects the language that ordinary people speak. It doesn't cling to usages that are no longer common and thus, to some, might sound pretentious. It also gives an implicit nod to spoken language, which is often less formal and somewhat easier to use than written language.
That's not to say Webster's is all about lazy English. But it does reflect a common-sense answer to what could be regarded as a prickly grammatical question.
So for those interested in the finer shades of meaning, here's the longer, more detailed explanation. In ordinary situations, the two words mean pretty much the same thing but are used for different points of view. In first person statements, shall is the traditional choice for present and future tense. In third person statements, will takes that role.
We shall meet the Jamisons for dinner and dancing this Friday.
vs.
The Jamisons will meet us for dinner and dancing this Friday.
Another, less common use of shall is in legal documents. Here the word tends to express both a more formal nature and a sense of obligation or duty.
The party against whom the judgment is decided shall be responsible for all legal fees.
The bottom line on this usage puzzle: unless you have a very specific reason for using shall instead, will is generally an acceptable choice.
© 2009 by AnnaLisa Michalski