IMO, all guest worker programs eventually succumb to fraud and corruption. It may start out with the noblest of intentions but as special interests intervene in the political process the "temporary" part of the Guest Worker plan becomes quite permanent.
Also, does anyone think that the entrenched underground Illegal Labor market is going to suddenly go away? I don't think so. I like Tancredo but sorry, guest worker programs no matter how structured are not the answer.
Suddenly? No, of course not.
However, the Tancredo plan also calls for more enforcement against illegals and their employers, while simultaneously providing a legal, documented, and regulated source for inexpensive, taxpaying guest labor. This provides both positive and negative incentives for employers to get out of the illegal labor racket, and for illegal aliens to leave and do the same.
Will some or many guest workers eventually apply for permanent status? Sure, and there's nothing wrong with accepting them since they've demonstrated a desire to assimilate and obey our laws, and also as long as those accepted for green cards are calculated in our annual immigration quotas.
We're going to have foreign nationals coming into our country for the foreseeable future. A moratorium is quite unlikely and is likely unnecessary. The key is for our country to get control of who enters, and the the key to that is a guest worker program that doesn't reward illegal aliens for their lawbreaking.