http://www.slcapex.com/[...]a fictional stock market simulation game operating for entertainment and educational purposes only and reinforce with: To be very clear, Capital Exchange is not a real-world stock exchange and does not offer opportunity for direct real-world investment or profit. Shares purchased on this stock exchange simulation game do not entitle you to any legal real-world rights to a listed virtual company. Please play accordingly!
and reading the tos of linden labs it says
The terms profit and earnings as used within the context of the CapEx.com website, and any claim of monetary value therein, relates solely and specifically to the valuation of $Lindens as specified in the Linden Lab Terms of Service, Section 1.4 (
http://secondlife.com/corporate/tos.php). [Note: should read 5.1]
The $Linden currency is a limited license right available for purchase or free distribution at Linden Labs sole discretion, and is not redeemable for monetary value from Linden Lab or from CapEx.com.
It doesnt matter one iota that you can redeem lindens for usd anywhere else. Just as a GLBSE "game token" it wouldnt matter if you use bitcoins somewhere else if you use the same TOS.