It remains to be seen how much of a RAM footprint 0.9 will take, but given all the work they've been putting into it, as well as their claims that 0.9 is going to have a narrower set of features (less of a 'kitchen sink' front-end) my hope would be that it would take up less RAM than 0.8. That said, I run 0.8 fine on a 2GB Macbook.
EDIT: Looks like they released it a day early... I'm currently downloading it and will report in shortly.