HDR is not an effect. Tonemapping an HDR with extreme contrast is an effect that can be achieved if you want to produce such an image. I think the term "HDR" gets used as a catchall phrase to describe many different things at different times in different contexts. Using a single RAW image and tonemapping it is not creating an HDR image. Using a single RAW image and producing multiple "exposures" from it in ACR, etc.and combining them is not creating an HDR image. You are not creating any more information in either of these processes than the original sensor can record in a single exposure. However, most of the posts here that use these techniques are described as "HDR" - technically, they are not; however, in this context the use of the HDR monicker is one of the description of the high-contrast, sometimes overdone, effect of tonemapping. You can tonemap any image you choose, even an 8-bit image - that is what you are doing when you make a "curves" or "levels" adjustment in PS. With HDR, tonemapping is necessary because you typically have much more dynamic range than a RGB monitor or printer can display.
Just to clarify, I don;t mean to be pissy about it, but I think when we are all using the term "HDR" we recognize that sometimes we don;t really mean a high dynamic range image, we mean the tonemapping effect that is often generated in Photomatix or other tonemapping routines required to display a 32bit HDR.
Again, with respect to HDR Panos, you can stitch together a full HDR pano in Hugin or PTGui or Photosphere without having to choose a combine-and stich, or stitch-and-combine workflow. But, suit yourself if you choose to kick it old school. Hugin (PC.Mac) and Photosphere (Mac) are free for nothin'.
Rock on.
Kirk