Unfortunately using encryption (like SSL) in your iPhone application generally subjects you to export compliance restrictions. This involves filing government forms and waiting some weeks.
Sample process for filing forms outlined: http://zetetic.net/blog/2009/08/03/mass-market-encryption-co...
There is an exception of "for purposes of authentication" but I'm not sure if it helps if you're always using SSL. Would be interesting to have someone chime in here.