That A) there was an update [someone plurked something new] or B ) someone responded to one of YOUR plurks.

That is someone plurking

There i plurked your plurk!

you can turn off the sound by clicking on the speaker symbol

you get more points for that too!

Why, hello there! You're now hooked up with more social media! Welcome to Plurk.

Hello!! Welcome!

hello and welcome...this is nice twitter that talks...

Ah, thanks. And thanks to all of *you* for the welcome.