It depends on the style of game you are running/playing. My current group tends to like the tactical combat quality of D&D so in this group Charisma is certainly a dump stat. However, I have played in other games more RP centered where it can be most helpful. I do, however, believe that in the majority of games out there it is considered the dump stat since in my experience hack 'n slash games tend to make up the bulk of D&D games being run. Best bet when one first joins a group to make it a dump stat until you get a feel for the group (that or play a Sorcerer, Bard, or Paladin so it serves some use). If you find that they are hack 'n slash then you are set. If not, then make do the best you can until that character dies and then make your next character more charisma focused.
Also... for the record I am sick of it when people think Charisma is purely personal appearance. It is "Force of Personality"... that intangible "something" that makes popular people popular.