Since a lot of forum members here mention having/using SIGG bottles, I thought I'd pass on crux of the email I got from ReusableBags.com, which is where I purchased my SIGG bottles from:
Basically, the news broke that SIGG's old liner contains BPA, but has not been shown to leach BPA. However, the new EcoCare liner (manufactured after August 2008) does not contain BPA or any other harmful chemicals.
This means that the old bottles are NOT unsafe, but you can still change them out for the new ones.
If you have bottles with the old (shiny copper bronze) liner, you can get them exchanged for ones with the new (dull pale yellow) liner until October 31st, 2009 via SIGG: http://mysigg.com/bulletin/exchange_program.html
Here is the page from ReusableBags that explains a lot:
They also mention a possibility of exchanging them at your local Whole Foods, but I'd call to check first.