If you are not prompted to update when you open LR and Bridge/Photoshop, in these programs go up to Help>Check for Updates.  Downlaod the .exe (PC) or .dmg (Mac) file to your desktop, then double-click to launch the installation.  When it is done, you can throw away the Adobe folder the install process placed on your desktop.    If you use LR and PS, be sure to update ACR as well — when you take a file from LR to PS, ACR is used to render the file.

It looks like a minor release to me (unless of course you own one of these new cameras and have been waiting to be able to process your raw files!)   According to Tom Hogarty, product manager at Adobe,the updates include the following:

Camera support for the following models:

  • Nikon D300s
  • Nikon D3000
  • Olympus E-P1
  • Panasonic DMC-FZ35**
  • Panasonic DMC-GF1

**Note that in Europe and Japan this model is marketed as the DMC-FZ38. Unfortunately, due to a metadata difference between these cameras, files from the DMC-FZ38 will *not* be supported until the next Camera Raw and Lightroom updates.

Release Notes:

  • Camera Raw 5.5 and Lightroom 2.5 include a correction to the demosaic algorithms for Bayer sensor cameras with unequal green response. Olympus, Panasonic and Sony are among the more popular camera manufacturers affected by this change. But the demosaic correction provides only a subtle visual improvement to the processing of those raw files.
  • Lightroom 2.5 corrects for the following problem in Lightroom 2.4. Lightroom 2.4 on Windows continued to display the import dialog when a memory card was detected regardless of the preference setting “Show import dialog when a memory card is detected.”