I cannot absolutely confirm that these are all web 2.0 companies - I got carried away just perusing all the logos that are starting to look the same, and, in this case, are pretty much cop-outs. Web 2.0 logos, part 1, focused on the many logos - wordmarks, really - out there using rounded and/or outline fonts. There are plenty of those in this batch too. Now we've added some simple graphical elements, too.
There are sound waves, and the talk bubbles. Squares. Circles. Lots and lots of circles. Built-in typographic elements like asterisks and stars. Some of these logos are nearly identical. Del.icio.us, Foopad, and Tilika have the same four-square pattern. Strmz and xanga not only use the same number of squares, there are even similar colors. And what about mozy and orange? Hope neither are in the market for a trademark.
I've noticed there are several “web 2.0 logo builders” out there now, too. That's gotta really piss off a lot of designers... I whipped out this Jules Says mark in Fireworks in a couple of minutes.
Click this image to enlarge it to 1188 x 821.
I understand that many firms, especially startups, can't afford to spring for a design firm to come up with a brilliant logo for them right out of the gate. There's a lot of laziness here, though, and certainly not much that's memorable.
Update:
Web 2.0 logos, part 3