It is possible to hack into a Mac. If you have physical access to the Mac then it is possible to hack into it. If you can persuade someone to download a script that will give you access to the Mac then it is possible to hack into the Mac remotely - this was the case at the recent pwn2own contest.

Another answer:

It is getting even easier as more people get MACs. The default for Mac computers is "accept all incoming." A program can now get into a MAC computer and take it over without the user realizing it. Anyone with a MAC should go into System Preferences and into security. You should change from the default to block all incoming. That way only programs that you send out, such as Safari can receive replies. No one can hack into your computer.

I'd say that it obviously is not safer than Firefox (or any other decent web browser), simply because it's still beta software, i.e. is going through a testing process. Also, Firefox and other browsers (Opera, Safari, Konqueror etc) have been around for quite a few years, whereas Chrome only for a few weeks. It is inevitable that it'll have some security issues during its "baby steps". However, Chrome uses a powerful web-engine, it's a very ambitious project of a huge web corp. and it has a touch of open source magic too.

However, now that google chrome has been around for a bit (now on version 4.1 08/04/2010), the browser has proved itself to be more secure than other competing browser such as Mozilla's Firefox, Microsoft's internet explore and apples safari. At the pwn2own competition, which sees computer security experts hacking various types of software for a prise, google chrome was, for the second time in a row, the last man standing. The competitors managed to execute arbitrary code by exploiting bugs in IE, firefox and safari, but not google chrome. This wasn't due to chrome having no bugs, in fact several of the competitors managed to identify a bug's in chrome, however, due to the sandbox feature which chrome employs, no one was able to exploit them.

Only in terms of general hacker focus, yes.

However, many Pwn2Own competitions have demonstrated the ability to hack a Mac in 20 seconds flat. Also, Apple are excruciatingly slow to patch flaws in Mac OSX, so if Mac OSX takes off in a big way, expect serious security implications.

If you are really looking for secure, a linux-based operating system may be the best way to go. Ubuntu 10.04 in particular is very useable as an operating system, and is relatively light on system resources (in comparison to windows vista/7, idk bout OSX)