I am making some wedding invitations for a friend and she singed up for one of those stupid wedding planning web sites to try to manage all of her stuff. She wants the url on her save the dates and on her invitations for people to check for details and to RSVP but the url is super ugly and long. Can I just use tinyurl or google's url shrinker and have it work for a few months at least? I know I don't control the redirect but is there a duration that the new url is valid for? If there is an alternative to doing this I would love to hear it too.
AFAIK they are permanent and last indefinitely.
URL shortners have been around for some time now, they aren't a recent development. I don't recall ever hearing about any of the major ones ever going down, although there were some concerns over bit.ly URLs recently due to some comments about linked content from Libya (the owner of the .ly TLD).
You should be ok for a couple of months ;)
You could also register a nice domain (like john-and-janets-wedding.com) and redirect it to the fugly one...
A domain that you registered lives for as long as you keep paying to renew it and after the wedding could be used to post a blog with Photos etc.