iPhone Bulletin: CSS hover effects are about to get a lot less popular
Lots of snazzy Web applications — 37 Signals’ Backpack and Basecamp come to mind — do a lot with hover effects. You point to an item, and hidden controls appear that let you expand it, or delete it, or edit it.
I don't think that works well (or maybe at all) with iPhone, because in a touch interface it's hard (impossible?) to hover without clicking. Prediction: this will, in short order, transform a bunch of Web 2.0 interfaces.
On the other hand, Jon Gruber was probably the first to observe that, since iPhone decided to avoid copy and paste entirely, email is the iPhone’s clipboard. That’s very good news for Web 2.0 services, since it’s easy to write interfaces that receive email (many already do) and so sensible things with them.