Is it considered bad for accessibility to use new or emerging web technology or formats?
No, actually we encourage users to implement technologies which can put additional useful content onto web pages. We just require that developers use these technologies in a responsible way. Macromedia Flash is a good example. A Flash site that has not been designed with accessibility in mind can be very frustrating or completely unusable to users of assistive technology. However, with a little forethought and a little extra effort these pages can be just as useful to users with different abilities.