hhmmm i've had a very different experience. i've never held a full-time working-for-the-man software development job but i've been freelancing for a bit over a year to bootstrap my own products. the money and flexibility is great. i got initial gigs because i'd been building my own product so i had something cool out in the world to point to. i think this is the single best way to get clients. have something that you - not you and a giant team of people, you - conceived of and built. when people see it (provided it looks good and works) they'll want to hire you. now i get gigs because i have happy clients and i'm a sociable person so they recommend me. people like working with me. so, build something you're proud of to show off and be a pleasure to work with. i've never gotten a gig through linkedin although recruiters contact me regularly. i have gotten gigs through hacker news, however, and they tend to be really good clients.
*edit: ALSO -- make friends with other freelancers and share your network! i've sent dozens of leads to people i know around Boston. this buys you social capital. people will reciprocate.