How can I get photographs off the iPhone 4 wirelessly?

Your iPhone 4 supports iOS 5.0, which can now sync photos wirelessly using Photo Stream.

For setup instructions, see http://support.apple.com/kb/PH2605

Eye-Fi has an iPhone app that will perform essentially the same function as the Eye-Fi SD Cards (wirelessly transfer photos to your computer and/or the web). More information can be found on their website - the catch is that you need to have an Eye-Fi card. No, it doesn't appear to actually use the card, but they give the app away to card owners.

I use PhotoSync to transfer pictures wirelessly from iPhone <-> iPad, and from iOS devices <-> computer. They have little computer utilities on their website to send and catch the photos on a PC or Mac. It handles bulk transfers too. I've had good luck with it so far.