The Releases section over at the GotDotNet workspace has three variants of v1.5:
"Source ZIP" with the code, "Web Files" with the runtime files (to update existing installs and do manual installs) and "Web Setup" which is an MSI to install the web site. Because the feature list keep growing, but we haven't done a language update for the various local languages, yet, updates to the string tables are welcome in the workspace source control system. And before you update: make a backup.
I am running v1.5 here without any problems. Let us know in the GotDotNet workspace message boards if you find any. I likely won't be able to answer any support questions this or next week.
Please note that you must not have the Whidbey Alpha version of ASP.NET mapped to the web into which you install this version; it can be present on the box, but not on the web for dasBlog. Otherwise you will get all sorts of assertions and error messages that aren't my fault ;)