Got this message in my inbox this morning.
Definitely not a Web 2.0 thing, not mentionning the IP address !
Here's an example of a perfect approach, by the new people search engine Spock.
Everything is in there, including the gentle way to please the customer : " You are one of the first people ...", so she feels proud to be considered as a VIP.
Also, you may notice the full URL link in post-scriptum : most of the Web 2.0 startups add such a link for you to copy & paste in case the direct hyperlink don't work. Here's my advice : always check if the sign-up confirmation email includes the full URL link. If not, it means the company / startup doesn't care that much about you...