As with any new operating system release, software compatibility must be considered.
The first compatibility consideration for Canon DSLR owners is that Canon EOS Utility reportedly does not work under Mac OS X Lion.
Update: Canon EOS Utility 2.8.1 is compatible, but the next two versions are not (thanks Vas).
Nikon has issued the following statement regarding Mac OS X version 10.7 Lion Compatibility (note that "plan to test" does not mean "currently functions properly"):
We plan to test the Macintosh versions of the following software applications for compatibility with Mac OS X version 10.7 (some older applications will not be tested). We will announce our plans regarding full compatibility once testing is complete.
- Capture NX 2 - ViewNX 2 - Camera Control Pro 2 - WT-4 Setup Utility/Thumbnail Selector - nik Color Efex Pro 3.0 - PC-PJ Transfer
We do not intend to provide compatibility with the following applications.
- Capture NX Ver. 1.x - Camera Control Pro Ver. 1.x - Nikon Capture series - ViewNX Ver. 1.x - Nikon Transfer Ver. 1.x - PictureProject - Nikon View series - Nikon Scan series - PictureProject COOLPIX Remote Control - WT-3 Setup Utility - Wireless Camera Setup Utility - Wireless Connecting Utility - nik Color Efex Pro 2.0
In addition, we do not plan to provide compatibility for other software, or SCSI- or serial-connection products. We apologize for any inconvenience this may cause