Yes yes I know, it's 3rd party software and I have posted this in the Peripherals forum! But as all the CD burner Q's are posted here, I decided this was the best place for it..
According to Mac User UK, There will be a new version of Toast. Toast 5 Titanium. From what I can tell, the main extra feature is back ground CD burning. It also supports more disc formats. Plus will be OS X friendly, both in terms of looks and use.
Also, on a related subject. Ahead software, makers of PC CD burning software "Nero" will be releasing a Mac version of it's software called "NeroMax"