There is one fascinating thing that I've seen from vendors over the years and that is their different perspectives on time when the talk about their products. I call it the "Temporal Perception" of a company. The basic challenge is that vendors talk about time as if the only important thing is their release dates and they have two different views on whether that date is in future or in their minds represents the present.
As an example I was talking to a vendor recently about their strategy and they kept talking about their next release (due in 2009) in the present tense. Clearly the development and marketing chaps need to be focused on that release but they were talking about it as if they'd already done everything, boxed it and shipped it to customers. Every question around the current issues and challenges was met with a "We've solved that in X" as if that would help me in the next EIGHTEEN MONTHS before the product shipped. Quite a few companies fall into this group and its easily the worst.
Another group of companies talks about their products in the future tense all the time saying "we haven't done that yet but it is on the roadmap" and then you find out they are shipping it next month but their perception is that anything that isn't already out the door is vapourware. They talk about a month as if its a distant possibility and even next week is just too far out to assume that it will happen. They have a long term vision of what they want to achieve and they'll talk about what they want to do but always in the distant future. This is a very small group of vendors.
Another one just refuses to recognise that there is a world beyond the next six months. Products are either shipping this quarter, just going into Beta or simply don't exist. They won't talk about the strategy and direction and won't admit to anything that hasn't been formally announced and passed through about a million lawyers first. They certainly won't admit that the product they are selling you today will be dead in 12 months. This is sadly common as well and doesn't help customers plan for the future.
I could go on and on about the different views on time and product that vendors have, fundamentally it comes down to their culture and perspectives and tends to fit into these three groups.
This really causes issues for companies when they work with software companies because the one thing that these vendors (except sometimes the ones in the middle group) are never focused on is the time frames that make sense for the customer and understanding the actual issues and challenges of the customer's present. So when you speak to a vendor make sure you understand their temporal perspective and recognise what that means to your relationship with them and what it will mean.