Interesting post made by Jonathan Schwartz about IBM not wanting to support its enterprise software on Solaris x86. You can find eWEEK article here. While Solaris 10 x86 is not widely used (yet) it's interesting that many big ISVs do support Solaris 10 x86. I'm really awaiting for IBM's response.
On the other hand I'm curious if Oracle is going to support 64bit version of its database on Solaris 10 amd64. At least I can't find any public statement about this.