1. Apple admits iPhone 3GS heat problems, iPhone 3GS tips to prevent overheating, from Apple and AT&T says iPhone 3GS is hot in a good way : Apple offered tips to avoid overheating the iPhone 3GS, but the tip list is written as if to suggest that users are more at fault than the hardware. Meanwhile, a supposed AT&T memo talks about how hot the iPhone has been in terms of sales. Keep reading for yet more iPhone news ...

2. Jailbroken iPhones leave users more vulnerable: Jailbreaking iPhones -- or altering them so that applications not digitally signed by Apple can be installed on them -- may let users feel they have more control over their handsets, but jailbreaking could well give miscreants the upper hand. Jailbreaking removes most of the security protections from iPhones, a security researcher warned this week.

3. DOJ officially opens investigation into Google Book Search: The U.S. Department of Justice confirmed that it has officially opened its investigation into a settlement involving Google Book Search in what will undoubtedly be a closely watched antitrust probe.

4. XHTML 2 language dumped for HTML 5: The World Wide Web Consortium will provide more resources toward development of the HTML 5 specification and will discontinue development of XHTML 2. HTML 5 is out in draft form, with a focus on multimedia for browser-based applications. It could be big competition for browser plug-in technologies such as Adobe Flash.

5. Oracle's European workers facing axe: Although Oracle's European performance was a highlight of its most recent quarterly financial report, the company could be about to lay off as many as 1,000 employees in Europe, according to a French labor union.

6. Mozilla launches Firefox 3.5, starts kill clock for older 3.0 and Review: Firefox 3.5 makes browsing faster, easier and more fun: After months of delays, Mozilla released Firefox 3.5 and more than 2 million users downloaded the updated browser within a few hours of its launch. Early reviews were mostly positive.