Besides iOS 4.2.1 slowing things down and frequently crashing apps. I've been having problems with websites I browse with lots of large images. The iPad has problems loading all the images on a single page with bluebox ? coming up instead of the actual images. Reloading and site does nothing to fix it. Browsing done on WiFi but no problem in desktop safari on the same WiFi network.
This can happen because the iPad Safari browser only allows a maximum of, I think, 25MB for storage of the JPG images on that site. When this limit is reached no more images are loaded.