Will my 15-inch, Early 2011 MacBook Pro with a 2 GHz Intel Core i7 and 4gb of RAM be able to handle this newest...landmark?

The pundits clamor for innovation, but it's the faithful who pay.

I'd expect Apple will support your MacBook for a few more years. But hardware upgrades are a fact of life. I've worked on a Mac since 1989. My combined hardware and software purchase upgrades easily tops $30,000. It hurts to think about it, but that's the price I pay to work in an industry that runs on Apple.

On the other hand, Apple stuff just works great and is great to work with. I'm not a techie. I just want the stuff to work and be trouble-free. Apple software is naturally intuitive. Their machines are reliable. Together it makes for an incredibly well-designed, beautiful product.

iMac (Mid-2007 or later)
MacBook (13-inch Aluminum, Late 2008), (13-inch, Early 2009 or later)
MacBook Pro (13-inch, Mid-2009 or later), (15-inch, Mid/Late 2007 or later), (17-inch, Late 2007 or later)
MacBook Air (Late 2008 or later)
Mac Mini (Early 2009 or later)
Mac Pro (Early 2008 or later)
Xserve (Early 2009)

In addition, the system requirements call for 64-bit, Intel-based Macs currently running Mac OS X 10.6.7 Snow Leopard or higher, with 8GB of free disk space for installation.

The computers and requirements listed above are nearly identical to OS X 10.8 Mountain Lion's requirements as stated by Apple in a support document. In fact, Mountain Lion stipulates that the base operating system on the install machine must be OS X 10.6.8 or later, a higher standard than Mavericks.

Usually with a new operating system version, some Macs are left behind as their hardware simply can't keep up with the demands of advanced software. For example, all Macs powered by at least Intel Core 2 Duo processors were able to run OS X 10.7 Lion, but when Apple launched OS X 10.8 Mountain Lion, some iMac, MacBook, MacBook Pro and Mac Pro configurations with Core 2 Duo CPUs were no longer supported. It seems that with OS X 10.9 Mavericks, however, all Mountain Lion-capable computers will be able to take advantage of the upgrade cycle.

http://appleinsider.com/articles/13/06/11/macs-capable-of-running-os-x-mountain-lion-likely-compatible-with-os-x-109-mavericks

That's how I watched Keynote today.