Users' machines tend to run extremely hot, causing the fans to cycle at a high rate and deplete battery power at an accelerated clip. ASD forum user "Ryan83" reports:
Fans running constantly at 6000 RPM without any program running - - just letting it idle or running solely itunes. Iphoto 09 unusable - - when you edit in full screen - - the screen shows colored artifacts all over. Internet has been very spotty and misbehaves.Similar symptoms are reported by many of the thread commenters. Typically CPU usage will spike when users do media-heavy actions with their systems, such as editing photos with Photoshop, cutting movies with Final Cut Pro, or watching media online at sites like YouTube or Hulu. Some users suggest that it could be a hardware issue with the actual fans, though this is unlikely (at least at first). Because most users report the problem after their upgrade to Snow Leopard, chances are it is a software issue. If left unattended, the problem could eventually lead to the fans, logic board, or other hardware becoming corrupt.
Some things to check
Be sure all your programs are Snow Leopard compatible. Several users reported that updating the notification utility, Growl, to the Snow Leopard ready version, 1.2, solved their overheating issues. Users should open Activity Monitor (Applications > Utilities) and take a look at any background processes that may be running. If any of those programs are not Snow Leopard compatible, they could be causing the excessive CPU usage and heat production.
When in doubt, especially if you are under AppleCare, taking your machine to an AppleCare Authorized Technician or an Apple Store is a good idea. You will want to avoid any future damage to your hardware as soon as possible. Keep in mind that a solution may involve reinstalling Snow Leopard. Be sure you have a stable and current backup of all your important data. As we have mentioned in recent articles, the 10.6.2 update for Snow Leopard is expected very soon and includes (based on information from beta releases) a myriad of fixes that may include a solution to the overheating issue. When the update is made available, drop by MacFixIt to get a rundown of all the included fixes.