So, does this basically obsolete other methods of anonymous transactions?  And since it is open-source, this could be adapted to any coin, no?  - Theoretically, yes, but each coin is different. It  takes time, skill and expense to adapt for each coin.

What is the difference between this and DarkWallet?  The principles are the same, but Obsidian works and it uses BLK instead of BTC.  BLK is of course faster, Proof-of-Stake and can be used alongside a working smart contract system, BlackHalo.  I just waited nearly an hour for a first confirmation for BTC earlier this evening.  That doesn't happen with BLK and its 66-second max confirmation times.

Are there any distinct advantages of using Blackcoin and Obsidian wallet vs. DRK, SDC, XMR? Again, Obsidian works and it uses BLK which is faster, Proof-of-Stake and can be used alongside a working smart contract system, BlackHalo.  Most importantly, Obsidian works without changes to the protocol, a fork or for "dark" features to be built into the coin.  This goes to mainstream adoption, a goal that coins with built-in "dark" features will have extreme difficulty achieving.

This statement could be expanded upon "Wallet Obsidian helps Blackcoin facilitate anonymous trading better than any other coin or system."
[/quote]  - The entire phrase is, "In concert with BlackHalo, Wallet Obsidian helps Blackcoin facilitate anonymous trading better than any other coin or system."  Using BlackHalo's smart contracts for cross-chain trading and commodity trading, just for example, are ways to trade that are completely anonymous and more so than any individual coin. In addition to the documentation on stealth wallets in the Obsidian announcements, review David Zimbeck's videos and posts on Halo.   Also, using BLK with Obsidian and Halo/NightTrader does not rely upon nodes or other central points to achieve anonymity.