This is a combination of the tables in Solaris (operating system)#Version_history and SunOS. I found it useful to make when reading them for my understanding, but I'm not quite sure which article it belongs in.

SunOS version Solaris Version Release Date Code base Description
Sun UNIX 0.7 N/A 1982 UniSoft UNIX v7 Bundled with 68000-based Sun-1 system
SunOS 1.0 1983 4.1BSD Support for 68010-based Sun-1 and Sun-2 systems
SunOS 1.1 Apr 1984
SunOS 1.2 Jan 1985
SunOS 2.0 May 1985 4.2BSD Introduced virtual file system (VFS) layer and the NFS protocol
SunOS 3.0 Feb 1986 4.2BSD + System V IPC Coincided with release of 68020-based Sun-3 series. Optional System V tape offered utilities and development libraries.
SunOS 3.2 Sep 1986 4.3BSD + System V IPC + some 4.3BSD First support for Sun-4 series
SunOS 3.5 Jan 1988
SunOS 4.0 Dec 1988 4.3BSD + System V IPC New virtual memory system, dynamic linking, automounter, System V STREAMS I/O. Sun386i support.
SunOS 4.0.1 1988
SunOS 4.0.2 Sep 1989 Sun386i only
SunOS 4.0.3 May 1989
SunOS 4.0.3c Jun 1989 SPARCstation 1 (Sun-4c) only
SunOS 4.1 Mar 1990
SunOS 4.1e Apr 1991 Sun-4e only
SunOS 4.1.1 Solaris 1 Mar 1990 Bundled with OpenWindows 2.0
SunOS 4.1.1B Feb 1991
SunOS 4.1.1.1 Jul 1991
SunOS 4.1.1_U1 Nov 1991 Sun-3/3x only
SunOS 4.1.2 Solaris 1.0.1 Dec 1991 Support for multiprocessor (SPARCserver 600MP) systems; first CD-ROM-only release
SunOS 4.1.3 Solaris 1.1 SMCC Aug 1992
SunOS 4.1.3C Solaris 1.1C Nov 1993 SPARCclassic/SPARCstation LX only
SunOS 4.1.3_U1 Solaris 1.1.1 Dec 1993
SunOS 4.1.3_U1B Solaris 1.1.1B Feb 1994 Earliest release for which Y2K compliance patches were available
SunOS 4.1.4 Solaris 1.1.2 Nov 1994 Last release of SunOS 4
SunOS 5.0 Solaris 2.0 Jun 1992 SVR4 Preliminary release, support for only the sun4c architecture. First appearance of NIS+.
SunOS 5.1 Solaris 2.1 Dec 1992 (SPARC) Support for sun4, sun4c and sun4m architectures. First Solaris 2 release to support SMP.
May 1993 (x86) First Solaris x86 release.
SunOS 5.2 Solaris 2.2 May 1993 SPARC-only release. Support for sun4, sun4c, sun4d and sun4m architectures. Support multithreading libraries (UI threads API in libthread)
SunOS 5.3 Solaris 2.3 Nov 1993 SPARC-only release. OpenWindows 3.3 switches from NeWS to Display PostScript and drops SunView support. Support added for autofs and cachefs filesystems.
SunOS 5.4 Solaris 2.4 Nov 1994 First unified SPARC/x86 release. Includes OSF/Motif runtime support.
SunOS 5.5 Solaris 2.5 Nov 1995 First to support UltraSPARC and include CDE, NFSv3 and NFS/TCP. Dropped sun4 (VMEbus) support. POSIX.1c-1995 pthreads added. Doors added but undocumented.
SunOS 5.5.1 Solaris 2.5.1 May 1996 Only release to support PowerPC platform; Ultra Enterprise support added; user and group IDs (uid_t, gid_t) expanded to 32 bits, also included processor sets and early resource management technologies.
SunOS 5.6 Solaris 2.6 Jul 1997 Includes Kerberos 5, PAM, TrueType fonts, WebNFS, large file support, enhanced procfs. SPARCserver 600MP series support dropped.
SunOS 5.7 Solaris 7 Nov 1998 The first 64-bit UltraSPARC release. Added native support for file system meta-data logging (UFS logging). Dropped MCA support on x86 platform. Last update was Solaris 7 11/99.
SunOS 5.8 Solaris 8 Feb 2000 Includes Multipath I/O, IPMP, first support for IPv6 and IPsec (manual keying only), mdb modular debugger. Introduced Role-Based Access Control (RBAC); sun4c support removed. Last update is Solaris 8 2/04.
SunOS 5.9 Solaris 9 May 2002 (SPARC) iPlanet Directory Server, Resource Manager, Solaris Volume Manager, extended file attributes, IKE IPsec keying, and Linux compatibility added; OpenWindows dropped, sun4d support removed. Most current update is Solaris 9 9/05.
Jan 2003 (x86)
SunOS 5.10 Solaris 10 Jan 2005 Includes x64 (AMD64/EM64T) support, DTrace (Dynamic Tracing), Solaris Containers, Service Management Facility (SMF) which replaces init.d scripts, NFSv4. Least privilege security model. Support for sun4m and UltraSPARC I processors removed. Support for EISA-based PCs removed. Adds Java Desktop System (based on GNOME) as default desktop.
Solaris 10 1/06 Jan 2005 added the GRUB bootloader for x86 systems, iSCSI Initiator support and fcinfo command-line tool.
Solaris 10 6/06 Jun 2006 added the ZFS filesystem.
Solaris 10 11/06 Nov 2006 added Solaris Trusted Extensions and Logical Domains.
Solaris 10 8/07 Aug 2007 added Samba Active Directory support, IP Instances (part of the OpenSolaris Network Virtualization and Resource Control project), iSCSI Target support and Solaris Containers for Linux Applications (based on branded zones), enhanced version of the Resource Capping Daemon (rcapd).
Solaris 10 5/08 May 2008 added CPU capping for Solaris Containers, performance improvements, SpeedStep support for Intel processors and PowerNow! support for AMD processors