Typically, the mother of the bride is quite involved in the excitement of the wedding planning, but often the mother of the groom is ignored, though she may want to be involved as well. If the groom is an only child or has only brothers (no sisters), the only way for the mother to "experience" the excitement leading up to the wedding is if the bride includes her in the pre-wedding activities.
Traditionally, the parents of the groom host the rehearsal dinner, prepare a list of names to receive invitations, and pay for the rental of the groom's tuxedo and perhaps the purchase of some of the wedding flowers, but that is about all. They tend to be largely forgotten when other decisions are made unless they are sharing in the costs of the wedding. If they are helping with the costs, they should definitely be consulted about decisions for which they may be paying.
If the groom's mother lives near the bride, she might be asked to go along to visit the ceremony or reception location, to go shopping for items needed for the wedding, or to go for a gown fitting (or even to shop for the gown). If she lives in another city, she might help plan a bridal shower for the bride in her hometown, or if she lives near the bride, she might help plan one for the groom's relatives (though her name should not appear on the invitation). If she lives in another city, she might plan a reception to be held after the wedding. If she doesn't live nearby, let her enjoy the pre-wedding excitement through e-mail, notes, and photos.
The bride and groom should jointly make the final decisions concerning the wedding, but keeping everyone informed and involved will strengthen relationships, both with the bride and her future mother-in-law and between the bride's mother and the groom's mother, and you will create lasting memories of shared experiences.