I found out that the new major release of bitcoind will contain support for the watch-only wallets: https://github.com/bitcoin/bitcoin/pull/2861. Anybody knows if there is available a binary package consisting of current stable version with this pull request merged in?
Depends on your OS, but building it yourself is crazy easy on OSX / Linux. It's an old enough pull request that it doesn't contain
$ wget https://github.com/sipa/bitcoin/archive/watchonly.zip
$ unzip watchonly
$ cd watchonly
$ make -j8
I'd supply builds for you myself, but there's absolutely no reason to trust that my binaries aren't backdoored or malicious in some other fashion.