Just weighing in on this issue --

I have the exact same discoloration issue, as mentioned in the handy graphic on someone's earlier post. My i300 is less than a month out of the box and this is already in place permanently. I'm a little wary of putting it in the freezer for an hour, but may try it before returning the thing.

Also I'll note that I don't have Sprint's replacement plan but at $4 a month it's certainly reasonable. I bought an extended warranty from Best Buy when I bought my phone originally ( a Nokia 6185) and have sense traded phones in for better models every 6-12 months, paying the cost difference until now, since the i300 has a value of $450, I can probably trade it up for another i300 or anything yet to come. Unfortunately the limited warranty runs out in July this year, after 3 years of overuse. But Best Buy informs me I can buy another one, for less than $90. That averages out to less than the $4 Sprint plan, but not really much different... Except that I don't know that Sprint will let you switch to a better phone when one is invented or launched.