In May bitcoin received a lot of publicity and many non tech people got involved, unfortunately, despite how brilliant the abstract idea, it was and it is still not ready for use by average consumer, someone using bitcoin at least have to know how NOT to trust a someone on the internet and have secure setup to store wallet. I think right now the next four problems stand on the way of wide bitcoin adoption, but it will take years to get established solutions
1.Creating a way to transfer funds into bitcoin system that would compete with credit card or PayPal in terms of convenience, e.g. you just need to sign up for credit card to start using it for payments.
2.Safe and secure e-wallet or lightweight bitcoin client for smartphone to use on the go, capable of making instant transfer to use in store or to buy something from vending machine, etc. Something like green address or MtGox QR voucher
3.Privacy and anonymity is important for long and short term survival of bitcoin. De-anonymizing process should be made not cost effective by implementing a method that would enforce use of one address per transaction and having sophisticated algorithm to select inputs and outputs for transaction to prevent consolidation. Enforce use of some form of proxy for bitcoin client to hide IP address.
4.Development of flexible software rather then all in one "take it or leave it" client, and eco system that would take advantage from it.
