When it comes to Adobe's Lightroom photography software I consider myself a super noob. I've been using it for over a year now but I'm still learning new things every few weeks. Yesterday I upgraded to version 2 and quickly discovered Lightroom can now run as a 64-bit application. Supported operating systems include Mac OS X 10.5.x and Windows Vista (64-bit).
Using Lightroom 2 64-bit on Windows Vista (64-bit)
The 64-bit version of Lightroom 2 will be installed on Windows Vista 64 by default. I've also heard reports of folks installing the 64-bit version on Windows XP even thought his isn't supported by Adobe. There's two installers that come with Lightroom 2 (setup32.exe and setup64.exe). Lightroom's installation routines will pick the appropriate installer for your operating system, but you can also launch one of them manually.
Using Lightroom 2 64-bit on Mac OS X 10.5.x
On Mac OS X 10.5.x, Lightroom 2 will be installed as a 32-bit application. To run the application as 64-bit you'll need to edit the Adobe Lightroom 2 application bundle in your Applications directory. Right-click the "Adobe Lightroom 2" bundle and select "Get Info." Or, single-click the application bundle and press command + i. Next, uncheck the "Open in 32 Bit Mode" and close the info window.
The next time you launch Lightroom 2 it will run in 64-bit mode. To verify this, open Activity Monitor (Applications - Utilities) and look for the Lightroom process. Check the "Kind" column and ensure it says "Intel (64 bit)."
If you want to read more about Photoshop, Lightroom, and Adobe's plans for 64-bit read John Nack's April 2008 blog post. The post is certainly old at this point and some of the obstacles presented in his post have been removed. Nevertheless, it's an in-depth look at what it takes to create 64-bit software.