According to an ZDNet article ( Sending code offshore 'vital for profits' - ZDNet UK News ) using overseas developers can really boost the bottom line of software development companies.
Of course, if it really was that easy then everyone would be doing it. There are barriers, particularly for smaller companies. That's where companies such as Redland Software are unique: a small company with an offshore software development office.
Large companies often partner with companies in the offshore nation. This can save al ot of time and effort and energy building a bridgehead into the offshore country. However, it also reduces a certain degree of control.
Very large companies build their own offices offshore (e.g. IBM in India).
Interestingly, the article reports that the developers in the host company often find that their work improves and the less skilled work is shipped offshore. This once again means that software programmers in the US and Western Europe need to continue to 'upskill' and improve their value added if they are not to be lerft behind.