Bitcoins' valuation is very complex. Google it and check it out if you want the specifics. It has no actual determination of value besides the fact that people view it as being worth money. However, the way the bitcoin system is designed, it limits supply and creation of bitcoins in relation to how many people are creating them. It requires resources to create, and this relates to its value. The more people "mining" and creating bitcoins, the more resources it takes to create one bitcoin.
Track BTC value here:
http://bitcoincharts.com/
LR is completely different. LR is backed by bullion (real gold metal). Its value is guaranteed, and therefore is much more stable. However, if e-Gold taught us anything, beware. These systems are not immune to government intervention, which can result in the loss of your funds. As for Bitcoins, the way the system is designed, it'd be damn near impossible for the government to even track any payments, let alone shut down the system.