The new Sony PS3 Slim is not only more compact than the currently available PS3 console, but actually offers some more advantages.
Sony has not actively promoted any advantages of the new PS3 Slim besides the small size, larger HDD (120GB) and the new low price of $299.99.
Over the last few days reports appeared that highlight hardware differences in the new Sony PS3 Slim that makes it even more attractive to buy.
The CELL CPU inside the PS3 Slim is actually new according to PC World. The original CELL CPU was based on 65nm technology and the PS3 Slim actually sports a new 45nm CELL CPU. The new 45nm may offer more performance and draws less power. This means the PS3 Slim could be snappier and use less power.

Engadget picked up a report that the new PS3 Slim actually supports Dolby TrueHD and DTS-HD Master Audio bitstream output now.

Like the lastest PS3 consoles the PS3 Slim is not PS2 backward compatible. In addition Sony also stripped the ability to install Linux on the PS3 Slim according to Wired.
This is bad news for scientists who build Linux clusters with PS3 consoles. On the other hand, I am pretty sure somebody will figure out a hack to install Linux on the PS3 Slim.

Overall you can say forget about the current PS3 console and go for the PS3 Slim. The PS3 Slim ships on September 1st for $299.99 from Amazon.com. Update: PS3 Slim Already Ships August 25th.