You can find yourself sandboxed upto 6 whole months.

Go into Google's webmaster tools and check external link count there.

The link: command is crap at best. It could however also mean you need more quality links as Google with worse than a pregnant horse when it comes to picking what links it does and doesnt like.

Personally I think Google's sandbox is mainly there to "forcibly encourage" webmasters to use adsense...