There are a few challenges with outsourcing and we've been running into them full speed.

Time zones matter
There are some advantages to having an outsourced group (developers, designers, etc...) in a separate time zone but there are a lot of drawbacks.   It's great to be able to shoot off a new set of tasks at 1am before going to bed and then wake up to new updates.   However, if you go with an outsourcing company that is halfway around the globe, you may have important changes that you need to submit at noon and you're not going to get the changes back until the next morning.  So, you're losing a day basically.  For my latest projects, I've asked to know exactly what hours the developers work and ask if they can have 2 teams so they can work around the clock.   There are very few outsourcers that work around the clock but if you can find one, it's a different world.

Language
Don't underestimate the challenges of communicating with outsourcers that do not speak fluent English.   Invariably, you will not have specified everything in your website / application design document and the developers will have to improvise at some point.  And, when they do, the improvisation will NEVER be as you thought it should be.   It seems that anything that's intuitive to me, is completely opposite for the outsourced developers.

The posts are going to be a bit slow as we are heads down 18 hours a day working on 9 different projects at the moment.