Microsoft have released a case study of how an investment bank (BarCap) has used SQL 2005 to developed a fixed income solution.
http://members.microsoft.com/customerevidence/search/EvidenceDetails.aspx?EvidenceID=13659&LanguageID=1&PFT=Microsoft%20SQL%20Server%202005&TaxID=20363
It's impressive how much resource MS throws on these early adopters - 11 consultants would normally cost around £15k a day.
I notice that the report mentions that readers and writers no longer block
http://msdn2.microsoft.com/en-us/library/ms130975.aspx
It will be interesting to see how much of a performance hit snapshot is - prior to 2005 alternatives such as "READPAST" or "NOLOCK" hints could be used - although this took a large amount of testing to ensure you got what you expected.
A few years ago I worked on a product using MS tools in beta
http://members.microsoft.com/customerevidence/search/EvidenceDetails.aspx?EvidenceID=1850&LanguageID=1
When I joined, the company had already been using .NET in beta 1 for around six months, and we went live with beta 2. Looking back, it was a brave decision, and for us developers lucky enough to be involved, gave us a chance to get ahead on the technology curve.
I am currently working on a similar system to the BarCap solution, although using SQL 2000 rather than SQL 2005. SQL 2005 has been in beta for donkeys, so I think the stability would be there, but I personally don't believe there would be a compelling case to upgrade.