This is an area of changeable weather so even if traveling in summer, be prepared for cooler temperatures especially in the morning and evening. Good hiking boots are best even for short hikes but on longer ones are essential.
Photo Equipment: A wide angle is great for landscape photography and capturing reflection photos of peaks from close range. A zoom is needed for wildlife and can double for macro photos of flowers. An external flash will make the difference in your people shots. Even outside, you often need to light your subject up in contrast to their surroundings.
Camping/Beach/Outdoor Gear: By all means, bring a tent, sleeping bags, mats and a cooker to not only make a trip to Mount Hood more affordable but also one closer to the nature you came so far to see.
Miscellaneous: D found some great spots in this area and she didn't even tell me she told me so. ;)
Be prepared for temperature variations. It may be sunny and warm one minute, but a couple of clouds and some wind can change the temperature drastically. Layering is always a good bet. Bring fleece and a down jacket, even in summer.
The photo below is my clothing for the 2 days of training and climbing. The guide service said to bring everything. I felt silly packing a down jacket while I was in Florida, but it came in handy on the summit.
Miscellaneous: Mountain Locator Units (MLU's) are highly recommended and have saved lives of unexpectedly stranded hikers and climbers. As of May, 2007, I do not think they are required, although they should be.