Powersave in snd_hda_intel was reenabled in kernel-184.108.40.206-43.fc11.x86_64. This causes audible pops, as described in bug #493972.
Setting power_save=0 in the module option fixes the issue.
The sound card is a Intel 82801I with the IDT 92HD71B7X codec, found in a HP Pavilion dv4-1125br.
Same here, very annoying. I just discovered this happening on my Dell M6400 laptop at work with ICH9 chipset. The power_save=0 module option is an appropriate workaround for me as well.
*** This bug has been marked as a duplicate of bug 523836 ***