The answer is No, IIS7 (still) does not support wildcard hostnames (see this). If you want to serve multiple domain on one website, the only workaround for now, as notandy suggested, is using a dedicated IP and doing it with DNS, which does support wildcards.
2013 Update
For completeness, IIS8 does not yet have this feature either.
2016 Update
Finally, IIS 10 in Windows 2016 supports wildcard subdomains.
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