Too close to refresh IMO - don't buy unless you really, really need it and can't wait.
Nothing has been announced though. We're assuming that the next refresh will be with Haswell chips, which are due 4 months from now. I wouldn't be at all surprised if it was 3 months after that that Haswell based Macs ship, so, 6-7 months at the earliest? That's not THAT close.
I suppose a little though, but, I think you could drive yourself crazy waiting on Apple.