Apple has released a knowledgebase document pertaining to the latest OS X 10.6.5 update, which mentions that the incompatibilities in OS X 10.6.4 that resulted in corrupt graphics and display flickering in the new MacBook Air systems have been corrected. The issue was in both the 11-inch and 13-inch 2010 model MacBook Air systems earlier this month.
Apple should be updating new systems with the latest OS update, so new purchases (especially those purchased online) should come with the latest OS X version and therefore not need patching; however, do be sure to run Software Update on any new MacBook Air systems to ensure they are fully updated before using them. Some off-the-shelf systems at retail outlets and even some in the queue from online orders may not have had the software fixes applied, and will need to be updated by the user.
This issue was a software-based bug, and any display issues experienced before this update likely will not have harmed the systems that showed them. In rare occurrences, faults in drivers or even applications can result in system components getting misused, resulting in overheating that may damage the machine; however, there usually are a number of low-level safeguards against these situations. Unless the flickering persists, previously affected MacBook Air systems should be fine.