Gmail was in beta for 4 years, and eroded the meaning of the term, IMO. I do see two different approaches to this though:
First, the "beta badge", where a company simply tries to signal that a product is early in the development cycle, and may/may not work as advertised. I don't see much value in that anymore, because users have many options, and putting buggy software out is silly. Rather, release often with smaller scope, test it well (ideally automatically), and collect feedback on the VALUE (not the STABILITY) of your features.
Second, the "limited release" approach to beta, where access to the product is by invitation only. With this, users explicitly accept the concept that they are providing some level of "testing" (functional, experience, usability...), and only opt in if they want to engage at that level. This is very useful, and many companies launch their product privately first.
Upshot - go for the limited release beta, and forget the "beta badge" :)