Saying thanks to those who did their jobs well, helped make a meeting possible, or just made your life easier is expected. It's not only expected, it can be quite detrimental if you forget to do it. People need to feel appreciated, especially if you aren't paying them enough, or asking them to do things above and beyond their pay grade.
However necessary an acknowledgement is, there is a downside to consider. In Seth's Blog, Seth Godin points out that at the beginning of a conference, a lot of time is spent thanking the organizers, the directors, the volunteers, and the host of people that made the event happen. Since there is usually a time crunch, the thanks are given hastily and are almost worthless for the recipients. On an even darker note, think of the attendees to the conference. They don't know or care about the people being thanked. All they know is they are sitting through five to ten minutes of their time wasted.
Seth's idea was to put a screen with a slideshow of the people you wanted to thank. You could start it ten minutes before the conference and let it loop so that it can be seen by all as they take their seats. It's a much more memorable way to thank your people without wasting your attendee's time.
That's a great idea, but what about your teleconferences? Before a video or web conference, you could load up a PowerPoint presentation that loops through the pictures and names of the people you want to thank. While your participants are logging into the audio and waiting for the meeting to start, they can be watching your slideshow. Then when it's time for the actual presentation, you just switch PowerPoints.
What if you are doing a no frills audio conference though? You still want to thank some people, but you don't want to waste anyone's time. Well, why don't you simply conclude your conference then thank everyone who deserves it before you say good-bye? If any of your participants have a pressing need to leave, they can. Otherwise, they can listen to who is important to you and those same people can feel appreciated.