Although on the down-side they're usually a bit low in performance because of the RAM, CPU and the GPU + if you're a touch typist, then most wouldn't like that fact that they come with smaller keyboards (again not on all the models, there are few Asus and others that comes with 95% of the standard keyboard size anyway).
Anyhow, unless you're going to use it for a certain purpose like video encoding which needs a lot of system resources then having a Netbook optimized operating system is the ideal environment for a Netbooks for speeding-up things a bit.
This is why some GNU/Linux distributions come with a separate version for the Netbooks with software packages optimized for those lower-end hardware, etc. The Ubuntu Netbook edition is the most popular example, although sometime ago they decided to stop develop it as a separate project and merge it into the Unity desktop which will behave more and more like a touch-sensitive device optimized OS in the future.
Anyhow, following the trend Pinguy OS developers also have come up with their own version which is optimized for netbooks called Ping-Eee OS 11.04. If you haven't heard, then Pinguy OS is another Ubuntu derivative that works out of the box. Meaning that it comes preloaded with all the proprietary codecs installed (including Java, etc) which is ideal if you don't have an internet connection available.
According to the Ping-Eee OS release forum thread, the OS was built (compiled, etc) using ASUS Eee 901 (Asus famous netbook brand name - Eee). Due to bit high memory consumption, Rhythmbox is replaced with Banshee instead. Other popular applications that's included in the default Pinguy OS such as Gnome DO, Glipper and Vineyard are also removed from the netbook edition.
Since most netbooks does not have a CD/DVD burner, burning utilities are also "skipped". The desktop looks clean and at the bottom has the popular application dock, Docky. I haven't installed the OS so cannot say much about the actual performance and I couldn't find a system requirements link either :/.
The downloadable ISO file has a size of 1.38GB which can be obtained from this page. Good luck oh and I should be thankful for Andrew from Webupd8 for the news.