FCK is enabled, but does not work for the iphone. This means that most content cannot be submitted.
The login block's text is too big causing a wrap. The width of the login block could be specified in em's.
pm_subscriptions is causing an error preventing many users from creating accounts because it is after the registration page.
On a 1600 monitor 400 px is about perfect, but on a 800 monitor it should be closer to 100px. Otherwise it will overlap the title.
Also, consider bringing zindex of title to front, and maybe even bringing the breadcrumb forward so the left vertical line does not protrude into the breadcrumb when it is 2 lines.
The OpenID button in the login block is not inline like it should be. This one is probably a problem with the theme.
The Feildsets have a background in the legend. This one seems to be all Internet Explorer's fault.