Generally, camera firmware updates fall into the random, infrequently occurring bug- or compatibility-fix category, and unless you've experienced the issues an update resolves, I suggest against updating your camera. Every now and then, though, an update comes out that--theoretically, at least--affects most or all users. The version 1.1 update for the Nikon D300 falls into this category. Buried among the usual host of minor changes, like "The Highlights playback option has been moved from Display Mode > Basic photo info > Highlights in the playback menu to Display mode > Detailed photo info > Highlights" are several important claimed performance improvements: for focus acquisition in dynamic-area AF mode, focus acquisition with contrast-detect AF and automatic white balance. I suggest all D300 owners check out the complete list of changes and the firmware update.
Though not quite as compelling as the D300's offering, Canon also announced one of those bug-fix firmware updates for the 50D (version 1.0.3).
Additionally, Olympus is offering firmware updates for five of its Four Thirds lenses to make them compatible with as-yet unavailable Micro Four Thirds Panasonic Lumix DMC-G1. They are:
- 14-42mm f3.5-f5.6 lens
- 40-150mm f4.0-f5.6 lens
- 25mm f2.8 lens
- 35-100mm f2.0 lens
- 35mm macro f3.5 lens