If you currently click on a ow.ly shortened URL you will be shown a server error page at ow.ly - not the URL you or the publisher intended you to see. Proponents of these services have so far ignored the main problem; trusting a third party. I guess they see the problem now when potential visitors to their site are stopped by a server error on someone else's site. The question of trust in this regard is especially important because these services has no working business model. Also any developer can create such a service in less than an hour making the barriers of entry for this service extremely low. Expect to see URL shortener services changing their tactics: Digg launched their already much hated DiggBar last week. This service unlike most other url shortener services wraps the actual landing page in a frame and adds a top-frame bar with Digg information. Ow.ly is also now doing this (unsure if this feature is new to this service). The problem for site owners is that they have no control over how these services will change. DiggBar is already "stealing" link-juice by having a digg-shortened link on Delicious instead of the original url. Also DiggBar and Ow.ly responds with a frameset (200 http status code) instead of a redirect (301 http status code). This can result in a lower pagerank as Google will not see the link from "Site X" to "Site Y" but instead from Digg.com to "Site Y". In my view URL shorteners are just plain evil. They add an extra unnecessary layer on the web.