As far as I know, it can only read the macros but not make new one. Office 2008 looks like a poor boy's Office 2004. Many things have been downgraded rather than upgraded. The apps don't talk smoothly with each other; some commands are outright stupid no matter what they advertise, some simply don't work as intended.
Since you are on Snow Leopard, your choice may be limited because Office 2004 is unstable under that OS. The major problem is PowerPoint that tends to crash and then becomes completely unresponsive. I have sacrificed quality for stability and bought 2008, although I do miss 2004.
They promise 2010 (or 2012?) version will get the macros back...